it is uncertain 后用that还是wehther,这两个词分别在什么情况下用?

it is uncertain 后用that还是wehther,这两个词分别在什么情况下用? 否定词缀的词不表否定吗比如说it is uncertain that 的反义疑问句用isnt阿 急求翻译：In a number of aspects, the behaviour of the Food and Drug Adminisitration(FDA) has接上：appeared to this writer as suggesting that it is similarly uncertain as to its proper role or function . In particular, th it's uncertain ______ the experiment is worth doing为什么不能用that 英语翻译No trading when it is uncertain.或者语法错误.希望简洁一点..... ——— is uncertain now.A.where did she put it B.where she put it求语法点. It is January 12th.January 12th 划线提问 Is it December 12th today? it is july 11th的问句 is it january 16th today? life is so peculiar .so uncertain .how little a thing it take to destroy you or save you 意思 It's uncertain ______ the experiment is worth doing.A.if B.that C.how D.whether life is so peculiar .so uncertain .how little a thing it take to destroy you or save you it is uncertain ( ) side effect the medicine will bring about,although about two thousandit is uncertain ( ) side effect the medicine will bring about,although about two thousand patients have taken itthatwhathouwhether 用适当的介词填空.(3).It is far____here.(4).Th park is east____the cinema. Today is saturday.用saturday提问 It is Nov.10th today.用 Nov.10th提问＿ ＿is today?＿is＿ ＿today? 英语翻译uncertain whether the port to which it is bound can be reached,and prevented by many impediments from returning to that it has quitted My birthday is .It is on July 19th 填空