1.如果是一个简单句,那么另一个动词必须使用非谓语形式,即可能是它的不定式/现在分词/过去分词形式,至于具体什么形式,必须根据具体的句意才能准确判断.
如：I got up early to catch the first bus.不定式to catch...做目的状语
I entered the room,singing and dancing.现在分词singing/dancing做伴随状语
You need to have your watch repaired.过去分词repaired做宾语补足语
2.如果是复合句或并列句,另一个动词可能也做谓语,即使用其谓语形式.
如：When I went to Beijing,I met one of my friends.
went/met分别做从句/主句的谓语
I watched TV and then went to bed.
watched/went做并列谓语.