平面连杆机构曲柄存在的条件是①()②()。
参考答案:最短杆与最长杆长度之和小于或等于其它两杆长度之和;连架杆和机架中必有一杆是最短杆
从右栏句子中找出左栏各句的正确应答,并将答题卡上该选项涂黑。
小题1: Would you like something to eat, Harry? A. It’s about three miles.
小题2: Hello! May I speak to Miss Green? B. Hold on, please.
小题3: What does your mother look like? C. Thank you.
小题4:Li Ming, you speak English very well. D. She is a teacher.
小题5: How far is it from your home to school? E. Yes, I’d like some rice.
F. She’s tall and beautiful.
我国每年总有一些地方发生水旱灾害,与此相关的因素是 [ ]
A、地形复杂
B、海岸线漫长
C、夏季风强弱变化
D、纬度位置