1£®He hasn't made up his mind whether he will go there.

→He hasn't   made the decision whether   he will go there.

2£®In many parents' opinion, teenagers shouldn't spend too much time online.

→Many parents   hold the view that   teenagers shouldn't spend too much time online.

3£®Modern science has proved that smoking can lead to many disease.

→Modern science has   given clear evidence that   smoking can lead to many diseases.

4£®She works hard.The fact is well known to us all.

→  The fact that   she works hard is well known to us all.

5£®Did he suggest that we start our work right away?

→Did he   make a suggestion that   we start our work right away?