当插图可以简化、缩短或使文本更容易理解时，应使用插图
A.illustrations should be used when they will simplify, shorten or make the text easier to understand. B.When illustrations can simple, shorten or r make the text easy for understanding, they may be used. C.Whenever diagram is can simple, shorten or make the understand, they could be used.正确答案A
