— Do you know now?
— Because we need to develop our life.
A. why we have more new inventions
B. why we had more new inventions
C. why do we have more new inventions
D. why did we have more new inventions
DNA is very useful for us, it many years ago.
A. discovers
B. discovered
C. is discovered
D. was discovered
If we have a ten-day holiday, we London with my parents.
A. visit B. were visiting C. will visit D. visited
I my friend Tim for 5 years.
A. know B. have known
C. knew D. will know
— Peter, where is your brother?
— He his English homework.
A. is doing B. does C. will do D. did
— Jack, you swim?
— Yes, I can.
A. can B. may C. need D. must