It’s necessary for human beings to breath _______ and plants can produce it.
#17259
A
CO2
B
H2
C
O2
D
N2
推荐题目
—We can see the signin the public places. What does it mean?—It means________.
#17198
A
NO PHOTOS
B
NO FISHING
C
NO PARKING
D
NO SMOKING
It’s nice _______ you _______ me with my lessons.
#16757
A
for, helping
B
for, to help
C
of, to help
D
of, helping