1。 and连接parts of sentences前面不一定add逗号 Theoretically, this convection would carry the continental plates along as though they were on a conveyor belt and would provide the forces needed to produce the split that occurs along the ridge。
(1)and 连接两个句子，主语一致省略，但前面并没有用逗号隔开! The enclosed seas are an important feature of the earth’s surface, and seriously require explanation because, in addition to the enclosed seas that are developing at present behind island arcs, there are a number of older ones of possibly similar origin, such as the Gulf of Mexico, the Black Sea, and perhaps the North Sea。
(2)and 连接两个句子，主语一致省略，但前面用逗号隔开了! 2。两个分别有独立主谓结构的并列句子中间用and连接, and前必须有逗号。
答：这里是完全投入，埋头苦干，集中精神做某事的意思，和ENGAGED意思差不多。详情>>
答：个评分来自于“EWG”的成分安全评价标准，美丽修行上的成分安全分以1-10表示，数字越小代表成分越安全。10分代表的是最高安全分，意味着该产品的成分非常安全，对...详情>>
