问一个英语词组look for ward to后面是加do还是加doing

问一个英语词组look for ward to后面是加do还是加doing 初二英语我搞不懂词组后面应该加to do 还是 doing 还是do 怎么办? look forward to是加doing还是加do? ask后面是加to do还是doing,还是do? fear 后面是加doing?do?还是to do? look forword to 加do还是doing find后面是加do还是加doing还是加to do? hard后面加doing还是to do refuse后面加to do 还是doing discover后面加to do还是doing? adjust to 后面加doing还是do? spend后面加doing还是to do?