题目内容

碳素工具钢的热硬性只有200℃，低合金刃具钢的热硬性可达300℃，高速钢的热硬性可达（）℃。

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制作量具没有专用钢种，可以用碳素工具钢、合金工具钢和滚动轴承钢代替。

A. 对
B. 错

正确选择下列工具材料：塑料模具钢（）。

A. CrWMn
B. W18Cr4V
C. 3Cr2MoS

三相电源做三角形联结时，（）。

A. 线电压等于相电压
B. 线电压大于相电压
C. 相线电压符合一定的比例关系
D. 线电压小于相电压

For the past several years, teachers have been mourning the 1 among people. They agree that 2. and other modern distractions have drawn students’ attention away from focused reading. However, this overstimulation has forced them to become 3 . English assignments prompt them to look for 4. that allow them to read around their texts and better understand them. Students may read shorter pieces nowadays, but they read them 5. .