be動(dòng)詞例句：
The man is a science teacher.
這個(gè)男子是一位科學(xué)教師。
Mary's new dresses are colourful.
瑪麗的新衣服色彩鮮艷。
I have been there before.
我以前去過(guò)那里。
My mother is in the kitchen now.
我媽媽現(xiàn)在在廚房里。
這四個(gè)都是陳述句，可以變成疑問(wèn)句，方法簡(jiǎn)單，把主語(yǔ)和“be”或助動(dòng)詞對(duì)換位置即可：
Is the man a science teacher?
Are Mary's new dresses colourful?
Have I been there before?
Is mother in the kitchen now?