=>
a/
1. She walked in without saying anything.
2. The fog prevented him from driving.
3. Neil wishes he hadn't sold his car.
4. The strange noise made the child run out.
5. No sooner had she arrived than things went wrong.

b/
1. He is said to be capable of swimming across this river.
2. It is uncertain whether they will turn out at the meeting.
3. The teacher sent out a reminder that we had to hand in the paper by the deadline.
4. It has become increasingly popular to learn English in our city.
5. As soon as he got off the plane, he was taken into custody.