It was not until dark ______ he found that itwas the correct way to solve the problem.

I can’t thank him too much, ____________ I couldn’t have finished the project in time.

The work he devoted his time to _____ worth praising.

Is this a pen— .

The environment is becoming worse and worse. I thinkwe should do something to ____ people ____ cutting the trees in order toprotect the earth.