Not until he retired from teaching three years ago _______having a holiday abroad .
240. It is an important problem. You should ________ before you draw a conclusion.
239. He_____ me 50 yuan and didn’t return it to me until last night.
238. --- Ought he to get down to his work at once? --- Yes, he _____. ought B. ought to C. must D. should to
237. Our teacher will _____ our class a picnic at the riverside tomorrow if the weather permits.
236. His order is _____ we ______ complete the task in five days.