What can smallpox cause?
contamination harmful substances vaccines photosynthesis extinction cellular respiration Destroy crops human disease
A B C D E F G H
Some smallpox viruses are maintained in laboratories.
smallpox causes human disease
What can smallpox cause? (A) contamination (B) harmful substances (C) vaccines (D) photosynthesis (E) extinction (F) cellular respiration (G) Destroy crops (H) human disease