题型:判断题 看图选择最佳答案。( ) 1. —Hello! How are you? — . A. I'm Jim B. I'm a bird C. I'm fine, thanks D. Nice to meet you ( ) 2. —What's this? — . A. It's an eraser B. It's a book C. It's two books D. It's a chair( ) 3. — ? —It's above the table. A. What's this B. How are you C. Is it your book D. Where's the book 查看答案
题型:判断题 以下关于各类阀门的叙述正确的是()。A、当管径DN>50mm时宜选用闸阀;管径DN≤50mm时宜选用截止阀B、旋塞阀可分为直通式、三通式、四通式C、蝶阀按传动方式可分为手动、蜗轮传动、气动和电动D、带传动机构的蝶阀必须垂直安装E、球阀流体阻力小,启闭迅速,密封性能好,被广泛用于管段的切断和流量调节 查看答案