At present, the ____ are too slow to car
题型:选择题
问题:
At present, the ____ are too slow to carry many people to Mars. [ ]
A. space shuttle
B. spacecrafts
C. spacecraft
D. underground
At present, the ____ are too slow to carry many people to Mars. [ ]
A. space shuttle
B. spacecrafts
C. spacecraft
D. underground