three hours是單數。因為你應該把three hours 當成一個整體,是一個時間段,所以應該把它看成單數名詞。它的謂語動詢用三單形式。
如, I've been waiting for you for three hours.
我等你已經三個小時了。
Three hours is 180 minutes.
三小時是一百八十分鐘。