1) I am disappointed that people have cut down all these trees
2) She sings ENglish songs well
3) The weather is hot so I open all the windows
4) A dripping faucet can waste 500 liters of water a month
5) I

b)
1) I am glad that you were able to come.
2) It's important that everybody should feel comfortable
3) I am surprised that she hasn't phoned
6) I was worried that you wouldn't come back that.
7) We were afraid that you would miss the flight
2) Your family should reduce the amount of electricity uses
7) You must remember turn off the fan when you leave to the classroom