题干
________my mother is very tired after a whole day's hard work, she tries to spare time for me.
A：Every time
B：Whenever
C：Even though
D：As
答案(点此获取答案解析）
C
________my mother is very tired after a whole day's hard work, she tries to spare time for me.
A：Every time
B：Whenever
C：Even though
D：As
2X + O2吸收，则X的化学式为( )