The boy often helps his father ___(wash) the car at weekends.

这里填wash.
一般两个动词,后面动词可以是ving/V原形/to do sth不定式,看搭配.
.1.V+ to do sth.如,
hope(vt.希望,盼望,期待),want(vt.想要,希望,需要),would like(愿意,意欲),
decide(vt.决定,判决),refuse(vt.拒绝,谢绝),choose(vt.选择,选定)
2.admit,avoid,consider,dislike,enjoy,escape,excuse,feel like,finish,forgive,give up,imagine,include,keep,mention,mind,miss,practise,put off,resist,risk,suggest,can’t help,can’t stand等动词后须用Ving形式作宾语,但不能用不定式.
3.feel、hear,listen to,look at,notice,observe,see,watch,have,let,make等
词后的宾语语中,不定式不带to,但是变被动的时候要带.