Before we go to the museum, we had better call first to make sure ... it is closed or not.

We ought to continue using fossil fuels until we manage to find cleaner ... of energy. 

The plastic covering the box was .... so much that it finally tore apart. 

The diplomat refused to answer the question asked by a journalist, saying that it was ...

The findings of the study are frequently referred to by different scientists because they're obtained from ... designed experiments. 

Unable to take good financial care of his family, the man decided to work in the afternoons to ... his yearly income. 