请问潮差是()。
A.相邻高、低潮的潮高之差
B.主、附港潮高之差
C.大潮与小潮之差
D.回归潮与分点潮之差
参考答案:A
The number of people invited ____ fifty, but a number of them ___ absent for different reason.
A.were; was
B.was; was
C.were; were
D.was; were
每题的备选项中,只有1个最符合题意。
采用红外分光分析法对游离二氧化硅进行分析时,其吸收光谱的波长中不包括( )。
A.12.5
B.12.8
C.14.4
D.15.9