阅读一小题，求解释（问题已简化）

Although in the mid-1940s term length at black schools was approaching that in white schools, the rapid growth in another important measure of school quality, school expenditures, may be explained by increases in teachers’ salaries, and historically, such increases have not necessarily increased school quality.

(B) The teachers in white schools had more time to cover material during a school year than did teachers in black schools.

(D) White schools did not change substantially in quality.

答案B 问COVER MATERIAL是什么意思？

LS,按你的解释，B就是正确的

因为文中说对于学期长度（TERM LENTGH）来说，黑人学校正在接近白人学校。但“接近”仍然是“少于”。

所以B对~