肺灌注显像剂的颗粒一般控制在()。
A.<10μm
B.10~60μm
C.60~100μm
D.100~600μm
E.>600μm
参考答案:B
22.______ in natural gas and oil, so this area is worth developing.
A.Being rich
B.It is rich
C.It being rich
D.To be rich
往复式氢气增压压缩机与补充氢压缩机在外形上的区别在于增设了()。
A.曲轴箱
B.十字头导轨
C.支撑环
D.辅助滑道