Câu hỏi: We know not what is good until we have lost it.

A. find

B. count

C. guess

D. learn

Câu 1: At times, this can be risky, and the keepers have been injured and one has been killed.

A. good

B. useful

C. healthy

D. secure

Câu 2: I love it when someone's laughter is funnier than the joke.

A. cry

B. shout

C. smile

D. frown

Câu 3: Keep only fish that you will eat; release the rest.

A. catch

B. hold

C. take

D. have

Câu 4: The plants and animals of the sea fall into three major groups.

A. small

B. chief

C. minor

D. main

Câu 5: Be quiet or you'll wake the whole house!

A. still

B. noisy

C. peaceful

D. tranquil

Câu 6: It's too far to ride to your grandmother's; you'd better take the bus.

A. remote

B. near

C. fast

D. besides