题干
Class is over. The students stop and start .
A：writing; to talk
B：to write; talk
C：writing; talk
D：to write; talking
答案(点此获取答案解析）
A
Class is over. The students stop and start .
A：writing; to talk
B：to write; talk
C：writing; talk
D：to write; talking
，则硼氮苯的二氯取代物(B3N3H4Cl2)的同分异构体数目为( )