Gilvarry, on the other hand, called on meteoroid impact to explain the production of ocean basins. The major difficulties with this model are that the morphology of most of the ocean basins is not consistent with impact, and that the origin and growth of continents is not adequately explained.

　　We agree with Donn at al. that the impact of large meteorites or asteroids may have caused continent formation, but would rather think in terms of the localized addition of energy to the system, rather than in terms of the addition of actual sialic material.

　　A mare basin is

　　[A]. a formula for determining the relationship between the depth and width of craters.

　　[B]. a valley that is filled in when a spatial body has impact with the moon or the earth.

　　[C]. a planetoid (small planet) created when a meteorite, upon striking the moon, breaks off a part of the moon.

　　[D]. a dark spot on the moon, once supposed to be a sea, now a plain.

　　2.The writer does not believe that

　　[A]. an asteroid is larger than a meteorite.

　　[B]. material from space, upon hitting the earth, was eventually distributed.

　　[C]. the earth, at one time, had craters.

　　[D]. ocean were formerly craters.

　　3.The article is primarily concerned with

【英语四级100篇精读荟萃中级篇三十五】相关文章：

★ 大学英语四级阅读理解长难句的六个大特点

★ 英语四级阅读理解长难句练习（六十九）

★ 大学英语的六级阅读中的填空题型

★ 大学英语四级考试阅读理解练习19篇之智力

★ 大学英语四级100条阅读难句-sentence 8

★ 英语四级阅读理解长难句练习（六十一）

★ 英语四级阅读理解长难句练习（七十四）

★ 大学英语四级阅读理解练习题（2）

★ 英语四级快速阅读原文

★ 英语四级考试阅读理解考前复习