It's uncertain _____the experiment is worth doing.能用if吗!又说whether可以的!到底选哪个?我想问个清楚!网上有的说if可以引导主语从句,有的又说不能,我想要个正确的答案!到底能不能!如果能的话下面这

it's uncertain whether the medicine will work on this cold的反义疑问句是什么? it's uncertain ______ the experiment is worth doing为什么不能用that It's uncertain ______ the experiment is worth doing.A.if B.that C.how D.whether The history of April Fool's Day or All Fool's Day is uncertain,but the current thinking is that it The history of April Fool's Day or All Fool's Day is uncertain,but the current thinking is that it It’s _____ today.Let’s ____. It‘s uncertain () the experiment is worth doing. A.if B.that C.how D.whether 求解释~O(∩_∩)O~ ____ _____ _____ _____,please?It's ten to nine It 's _____ for people _____ _____ the busy streets It's used for _____ _____ _____(探索太空） 英语翻译What's it used for?It's _____ _____ _____ metal It's cloudy today.的同义句It's _____ _____ _____ today. It's _____ seven twenty.填介词 It's time to ___ _____ It's time to ___ _____ It's u _____ the chair.填空 Let's keep it _____ feeling cold. Children's Day come a _____ it.