He started to study ecology and decided to ________ his whole life to science.[ ]

You may have your own decision on this matter,and I have little doubt _________ you’ll succeed.

Our chemistry teacherannounced that he would do the experiment in a differentway we might findinteresting

189. I tried to ____ in my speech we wereall grateful for his help.

The old man was _______ sad _______ say a word when he heard the bad news.