.They were __________ to produce carbon,
题型:选择题
问题:
.They were __________ to produce carbon,nitrogen,water and other gases.
A.in time
B.at a time
C.at one time
D.on time
.They were __________ to produce carbon,nitrogen,water and other gases.
A.in time
B.at a time
C.at one time
D.on time