团队合作因为成员间的背后捅刀子而变得困难。

Teamwork became difficult because of the ___back-stabbing among members.

办公室里充满了暗箭伤人的行为，有些人为了升职不惜在背后诋毁同事。

The office is full of ___back-stabbing behavior, with some people badmouthing colleagues behind their backs just to get promoted.