右半结肠癌引起的梗阻属于（）
A.机械性绞窄性肠梗阻
B.血运性肠梗阻
C.痉挛性肠梗阻
D.麻痹性肠梗阻
E.机械性单纯性肠梗阻
参考答案：E
阀短路保护需要检测（）。
A.换流变阀侧Y绕组
B.换流变D绕组的电流
C.直流极母线电流
D.直流中性线上的电流
Tom urged that he _____ with so much work while his parents went on a snorkeling trip. [ ]
A. was left alone
B. not be left alone
C. will be left alone
D. isn't left alone
