The boy failed the exam because he _____ a lot of time playing the computer games.

A．spent

B．paid

C．used

D．cost

缆索护栏中缆索材料性能测试项目包括（）等。

A、钢丝抗拉强度测试

B、反复弯曲及扭转测试

C、缆索捻制方法及直径

D、防腐质量测试