第10题: [单项选择]钢筋混凝土受弯构件施加预应力,对于构件正截面开裂弯矩和破坏弯矩的影响是()。 A. 受拉钢筋施加预应力会提高开裂弯矩和破坏弯矩,而受压钢筋施加预应力则将降低开裂弯矩和破坏弯矩 B. 受拉钢筋和受压钢筋施加预应力都会提高开裂弯矩和破坏弯矩,其中前者的效果更好些 C. 受拉钢筋施加预应力会提高开裂弯矩,但不影响破坏弯矩。受压钢筋施加预应力将降低开裂弯矩,对于破坏弯矩则需视受压钢筋的张拉应力而定,张拉应力较大时会少量地降低破坏弯矩,张拉应力较小时则会增大破坏弯矩 D. 以上都不对 参考答案:C
第11题: [填空题]Scientists believe that the things people do that send ______________________ gases into the air are making our planet warmer. 参考答案:greenhouse 答案解析:Scientists believe that the things people do that send ______ gases into the air are making our plan