В пропусках возможны: can, ought to, may, might, should, сould. 10) New drivers ought to take a test in order to get a driver's license. They have no choice.
15) A: … go to work today? B: No, I don't because it's Sunday.
16) Sasha … e-mail her homework to her teacher because she forgot to take it to class yesterday.
17) John … finish the report quickly because the deadline is today at 4 pm.