1.be covered in 被...覆盖
It could, too, be covered in oceans, perhaps completely.
这颗行星也可能完全被海洋覆盖。

2.expose to 暴露于
The pollution of drinking water make people expose to the inorganic arsenic and cause the chronic arsenic poisoning.
工业污染及水源污染使人暴露于无机砷的环境，导致慢性砷中毒。