- 搜标题
- 搜题干
- 搜选项
单项选择题
The ____ difficulties of the country are not to be made light of.
The ____ difficulties of the country are not to be made light of.
A、economics
B、economic
C、economical
D、economically
A.
y1，z1是主惯性轴，而y，z不是
B.
y，z是主惯性轴，而y1，z1不是
C.
两对轴都是主惯性轴
D.
两对轴都不是主惯性轴
