SUGGESTIONS:

1.he said "Let's use public buses instead of motorbikes."

=>He suggested that

=>He suggested that public buses

2.The woman said, "what about having a plumber check the cracks."

=>The woman suggested that

=>The woman suggested that the cracks 

3.Why don't you repair the computer,Ba?", she said

=>She suggested that

4.I wanted the children to study harder for the exam. 

=>I suggested that

5.The principal said "Let's have students clean up the school yard every weekend"

=>The principal suggested that the