【简答题】聚丙烯的立体异构包括______、______和无规立构。
【单选题】Not the teacher,but the students ____ looking forward to seeing the film.
【简答题】聚丙烯的立体异构包括全同()、间同()和无规立构。
【单选题】一圆柱正齿轮,模数m=2.5,齿数Z=40时,齿轮的齿顶圆直径为 。(难度:A)
【简答题】阅读理解。 It's hard to make friends if you stay at home alone all the time. Be outgoing, get out of the house and do things with other people. It's easier to make friends when you follow these: Show peopl...