You should report your trip to the school ___ you travel out...
You should report your trip to the school ___ you travel outside the city.( ) A. unless B. until C. if D. while答案unless除非;until直到;if如果;while在……期间。根据"you travel outside the city"可知,如果你出城,就应该向学校报告你的行程,应用if来引导条件状语从句。...