题目

Albert Einstein was born in 1879. As a child, few people guessed that he​ a famous scientist whose theories would change the world. A . has been B . had been C . was going to be D . was 答案：C一座建于若干年前的水库大坝的横断面为梯形ABCD，如图所示，其中背水面为AB，现准备对大坝背水面进行整修，将坡角由45°改为30°，若测量得AB=20米，求整修后需占用地面的宽度BE的长．（精确到0.1米，参考数据：≈1.414，≈1.732，≈2.449）