The clay on the walls has been removed to expose the original bricks underneath.

The report exposes the weaknesses of modern medical practice.

His work exposes him to a great deal of stress.

We want to expose the kids to as much art and culture as possible.

【考例1】Pygmy rabbits also rely on winter cover by digging tunnels through the snow to escape predators, but lesser snowfall is leaving them exposed. (浙江2012阅读理解A篇)

【考例2】However, it is important to be aware of these dangers because everyone is exposed to air pollution regardless of lifestyle choices. (陕西2011阅读理解C篇)

4. have a gift for

【点拨】have a gift for意为"有......的天赋"，后跟名词或动词-ing形式。如：

Donald has a gift for languages.

Patrick has a gift for making friends easily.

【考例】Professor H. Siegel, honored by Kentucky Educational Television as "the best math teacher in America," is a devoted teacher and has a gift for explaining mathematical concepts in ways that make them seem clear and obvious. (北京2012阅读理解A篇)

5. call on

【点拨】call on意为：①访问，拜访，探望；②邀请，要求（某人讲话等）；③请求，要求（某人做某事），要求......介入，号召，呼吁。如：

I shall call on Sandra tomorrow.