题目

With the Entrance Exam approaching, I feel more and more stressed. It will ruin my college dream _____ I take action now as soon as possible. A . since B . once C . until D . unless 答案：D长度为9、12、15、36、39的五根木棍，从中取三根依次搭成三角形，最多可搭成直角三角形的个数是 [     ]A．1B．2C．3D．4