纵波垂直法探伤中,由于()的结果,靠近侧壁探测时缺陷回波低,远离侧壁探测时缺陷回波高。
A.侧壁干涉
B.波的叠加
C.波的绕射
D.波的衍射
参考答案:A
阅读短文,选择正确答案。
Sally is an artist. Usually she gets up at ten in the morning. Then she eats breakfast and does morning
exercises. She likes painting at night. She believes (相信) she does best at night. She never watches TV in the
evening. She goes to bed late. She teaches lessons, too. She is a good teacher. Her students like her very much.
She goes to school by bike and comes back on foot. Now Sally lives in the country. She is preparing for her
first painting show. She is working hard and she is very excited.
1. What does Sally do?
A. A doctor.
B. A nurse.
C. An artist.
2. Does she get up early in the morning?
A. Yes, she does.
B. No, she doesn't.
C. Yes, she doesn't.
3. Does she watch TV in the evening?
A. No, she doesn't.
B. Yes, she do.
C. Yes, she does.
4. How does she go to school?
A. By bike.
B. By bus.
C. On foot.
某工程出现安全质量事故,该事故并未造成人员伤亡,但造成直接经济损失达800万元,间接经济损失300万元,按国务院发布的第493号令《生产安全事故报告和调查处理条例》规定,该事故属于()
A.一般事故
B.较大事故
C.重大事故
D.特别重大事故