*Question*
It is not always easy to understand inventions and new developments in science. To understand fiber optics , however, you can try an experiment. Put a drop or two of milk into the glass of water. Turn off the lights. Shine the light from your flashlight  through the top of the glass at an angle  of about 45 degrees. Put a piece of white paper against the glass when the beam of light is shining. Move the paper so you can see where the beam is coming out of the glass. You should see a spot of light. Some of the light has passed through the water and through the glass. You see it on the paper. You also see another beam going down into the glass. It is being reflected down into the glass. Next move the flashlight so that the beam is coming straighter down(30 degrees) into the water. You will see the same phenomenon: some of the light is reflected back into the glass. And some escapes out. Now move the beam of light from the flashlight slowly up until you cannot see any light escaping. This point is called the "point of total internal reflection." The word internal means "inside." All the light is staying inside the glass. There is no beam showing a bright spot on the white paper. All the light energy is inside the glass. The glass of milky water is like a strand of glass. A fiber optic tube is a bundle of long thin strands of glass, really many tubes. However, the principle  is the same: at a certain angle, all the light energy that goes into the glass fiber comes out the other end. Light is energy. Sound is energy. Radio waves and electricity are both energy. They can all be changed into light, and as light they can all travel along a glass fiber. Light travels at the rate of 186,000 miles per second. Therefore, a message can travel that fast in a glass fiber. This is the principle, or law of nature, that makes fiber optics work. In the experiment,_makes the biggest difference. A) the angel at which to shine the light from the flashlight B) the amount of water in the glass of milk C) the number of drops of milk to pour into the glass of water D) the size of the hole through which to shine light from the flashlight
**Answer**
A

*Question*
Each of us would like to be trusted by parents, because we all want to get freedom. Parents are more likely to give us our freedom if they trust us. If you want your parents to trust you more, you have to show them through your actions.    Let your parents know what's going on at school and with your friends. If you truly can be trusted, then you have nothing to hide, right? Keep your bedroom door open when you are back. Do not be crazy when they see what you are looking at on the Internet. Invite your friends to your house to meet your parents.    When you do something wrong, it can break trust. Broken trust takes a long time to rebuild.    It's not easy dealing with your parents when you've broken their trust. But, it can be done. It's not talking about groveling and sweet-talking them into trust. I'm talking about getting them to respect you again.    I find it easy to make the mistake of no telling my parents things I've done wrong, hoping they won't find out. There are lots of reasons:    I don't want to get into trouble;    I don't want them to be disappointed or get mad at me;    I don't want to lose their trust;    I don't think they will ever find out.    And the list goes on and on. But they find out somehow, and then you're in hot water. Of course, even if Mom and Dad never find out, you still know about.    Most parents will respect you more for coming to them and telling them yourself. Doing so shows honesty, responsibility and maturity . If you can't tell them face to face, you can try writing a note.    Trust can't be built in a day or even a week, but you can gradually do things to help your parents build trust in you. What would children like to get from their parents according to the passage? A) Money. B) Freedom. C) Love. D) Clothes.
**Answer**
B

*Question*
Parents fear they are putting too much pressure on their daughters to reach their academic potential, the president of a girls' school body has said. Incoming Girls School Association head Jill Berry said parents were worried about achieving a balance between school achievement and happiness.  Mrs. Berry also said that girls could put themselves under a lot of pressure. A poll of 1000 parents surveyed for the association said their top concern was their daughter's education. Girls tend to outperform boys in all stages of their education, and this can lead schools to assume all girls will do well.  Mrs. Berry said, "There is no doubt that many mothers and fathers are worried about getting the balance right between their daughters realizing their academic potential while at the same time being happy and safe." Mrs. Berry said in her experience girls had very high expectations of themselves. "That's a positive thing and we want them to aim high. But sometimes we do find a girl is being unrealistic in her aspirations or putting herself under unreasonable pressure. It's not necessarily pushy parents--it can come from the girls themselves."  But parents, too, wanted support to get the balance right between caring and being involved in their children's lives and not being "helicopter parents", she added.  Women could be perfectionists and it was important to encourage girls to listen to their body, which could give warning signs of too much stress, she added. "Bright motivated high achieving girls with high expectations of themselves are more susceptible   to eating disorders," Mrs. Berry said, "But girls' schools are usually very good at dealing with these things."  It was a teacher's job to help girls "to have it all", but to help them deal with inevitable   disappointments as well, she said. Mrs. Berry believes that  _  . A) girls' pressure mainly comes from their parents B) it's not necessary for girls to aim high C) girls who aim high usually end up disappointed D) girls' pressure mainly comes from themselves
**Answer**

D