there is与 It's 有什么固定句型 一直不知道表示可能性的词possible之类的词应该用哪个

there be +名词+介词短语 （如果名词是并列的,那要遵循就近原则.就是靠近be的是单数,就用there is； 复数,就用there are）
there be +名词 +doing
it's +形容词 （of /for sb.）to do 形容词如果是表示人的品质,就用of 例如 It's nice/ clever of you to do It's difficult/ imprtant for sb.to do
It's +名词 +to do It's our duty to protect the environment.
It's time to do 该干...了
It's possible + to do 做什么是可能的
maybe,Probably是副词 经常放在句首.