We’ve tried every _______ to solve the problem.
Although the entrance to the cave was very narrow, those visitors managed to________through it.
I don't think Tom's remarks are________;he is not supposed to say so.
So suddenly ________that the animals in the zoo looked very frightened during the total solar eclipse (日全食).
—Have you finished your book report?—Not yet. I couldn't________on it with so loud music next door last night.
Once we have________some knowledge, things do not become more difficult, but comprehensible.