betoblame,betopraise什么意思?两道例句：（1）John,ratherthanhisroommates,istoblame.（2）Ithinkmary,ratherthanLucy,istopraise.问：这两句话不是被动语态吗?为什么会用betodo?类似于这种形式的短语

Question

be to blame,be to praise什么意思?
两道例句：
（1）John,rather than his roommates,is to blame.
（2）I think mary, rather than Lucy, is to praise.
问：这两句话不是被动语态吗?为什么会用be to do?类似于这种形式的短语有哪些?

Answer 1

详阅：
【不定式】to blame,to let,to seek,to rent,to find用【做表语】时,通常用主动表被动意义.
例如：Who is to blame?该怪谁呢?
She was in no way to blame.决不应该责备她.
A better way is yet to seek..还得找一种更好的办法.
The taxi is to rent.汽车出租.
Much remains to find.有待探寻.
The house is to let.房子出让.