[tóu jī]
（利用时机谋取私利） speculate; seize a chance to seek private gain; be opportunistic
join the revolution in order to seek personal gains
投机革命
（见解相同） congenial; agreeable
talk very congenially; have a most agreeable chat
谈得很投机
If two people have nothing in common, exchanging a few words can be difficult.
话不投机半句多。