THE ENVIRONMENT PRACTICE TEST 1I. CHOOSE THE WORD OR PHRASE THA...

11. - 200 CAU TRAC NGHIEM KQ ANH 9 -BAI 6-7
200 CAU TRAC NGHIEM KQ ANH 9 -BAI 6-7

11. I’m worried ___________ many people have littered in public places.

a. that

b. when

c. if

d. how