交接班时各车场固定()必须固定使用,不得()。
参考答案:分类线;混线
最早测量恒星距离的方法是:()。
A.三角视差法
B.分光视察法
C.星际时差法
D.自转视差法
I tried hard to _______ a mental picture of what might have happened, but however hard I tried, I simply couldn’t _______ it.
A.make, make
B.take, get
C.draw, make
D.attract, do