测量计算的基准面是什么?
参考答案:
参考椭球面。
He__________ he would be able to leave tomorrow, but it's beginning to took difficult.
A.hopes
B.was hoping
C.had hoped
D.hoped
不同分子大小的蛋白质混合物流经凝胶柱层析时,小分子物质因体积小最先被洗脱出来。 ( )