His friends asked him ________ up smoking.
A:give
B:to give
C:gave
D:giving
已知2x6y2和﹣13x3myn是同类项,则9m2﹣5mn﹣17的值是( )
“人要学会走路,也要学会摔跤,而且只有经过摔跤才能学会走路。”这句话告诉我们 ( )