What is Date, when Meet is 'World Championships', when Nationality is 'United States', and when Time is '1:46.68'?
CREATE TABLE table_60954 (
    "Event" text,
    "Time" text,
    "Nationality" text,
    "Date" text,
    "Meet" text,
    "Location" text
)
SELECT "Date" FROM table_60954 WHERE "Meet" = 'world championships' AND "Nationality" = 'united states' AND "Time" = '1:46.68'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: What is Date, when Meet is 'World Championships', when Nationality is 'United States', and when Time is '1:46.68'? ### Input: CREATE TABLE table_60954 (
    "Event" text,
    "Time" text,
    "Nationality" text,
    "Date" text,
    "Meet" text,
    "Location" text
) ### Response: SELECT "Date" FROM table_60954 WHERE "Meet" = 'world championships' AND "Nationality" = 'united states' AND "Time" = '1:46.68'