He_______ his students lessons though he was not feeling well.
A:insisted on giving
B:insisted to give
C:insisted to giving
D:insisted given
下列少数民族与其民族节日对应正确的是( )
①氦气②甲烷③干冰④食盐⑤钛合金⑥葡萄糖
选择相应的物质填空(填序号).
下图是我国某地新开辟的自然风景区示意图,据图,完成下面小题。