找出下列各组单词中划线部分发音不同于其他三个的词
The big trees __________ some shade __________ us.
—________? —It was sunny.
Vivien worked very hard at all her lessons________ become the top student in her class.
—Excuse me, where is Children’s Park, please? —Take the No. 5 bus and _____________ at the fifth bus stop.
— I think English is __________ unimportant subject. — I don’t think so. It is __________ useful tool when we talk with foreigners.