Our teacher told us __________.
A:what life on Mars is like
B:how life on Mars is like
C:what life on Mars was like
D:how life on Mars was like
我国推广食用的碘盐为在食盐中加入一定量的碘酸钾(KIO3),在碘酸钾中碘元素的质量分数是( )
整亿的数改写成用“亿”作单位的数,只需去掉末尾的( )个0,再添写一个“亿”字。