先take是正式,have多随意.所以take a look at 有检查之意,较为严肃,have a look at就是去看看,比较口语和生活化.take a look in 后可以接地点,比如Because I bought the ticket which I could take a look in the palace.但是at后面接具体的事情或者抽象的东西,比如Have a look at what happens.