造成构件尺寸缩小和变形的主要原因是焊接时材料的（）。
A、焊接应力
B、热胀冷缩
C、材质
D、尺寸大小
参考答案：B
Last year, my brother , who is a software developer, earned ______ my sister, a teacher in a senior middle school.
A twice as many as B as many as twice C twice as much as D as much as twice
溃疡性结肠炎患者腹泻的机制是
A．肠内容物渗透压高，导致小肠渗透性腹泻B．炎性大肠粘膜对水钠吸收减少C．结肠隐窝胆盐分泌增加D．大肠粘膜对Na+吸收减少
