【单选题】地球上昼夜现象形成的“完全必要”条件是 ①地球本身不发光 ②地球在不停地自转 ③有一颗并且只有一颗太阳照耀着地球 ④地球是一颗不透明的天体 ⑤地球只有一颗天然卫星——月球 ⑥地球在不停地围绕着太阳公转 [ ]
【多选题】、火法炼铜的工艺过程主要包括四个步骤( )
【单选题】一I wonder _______________________. 一You should call her to make sure, so we can know where to pick her up.
B.
whom Lisa is coming with
C.
whether Lisa is coming by train or by air
【单选题】We have to make sure that her _________( = breathing passage) is secure.
【简答题】I reached for her hand and reassured her that we were going to make it .
【单选题】We have to make sure that her __________(=breathing passage) is secure.
【判断题】火法炼铜的工艺过程主要包括四个主要步骤:造锍熔炼,铜锍吹炼,粗铜火法精炼和阳极精炼。