皮皮学，免费搜题
登录
搜题
【单选题】
( )是利用旋塞阀体两者的重合程度来截止和调节流量的,它启闭迅速,经久耐用,但由于摩擦面大,受热后旋塞膨胀,难以转动,不能精确调节流量,故只适用于压力小于1.0 MPa和温度不高的管道上。A.
止回阀
B.
蝶阀
C.
旋塞阀（）
D.
安全阀
拍照语音搜题，微信中搜索"皮皮学"使用
参考答案：
参考解析：
知识点：
皮皮学刷刷变学霸
举一反三
【单选题】—_____ last Sunday? —It was cold and snowy. [ ]
A.
What was the weather
B.
How was the weather
C.
How was the weather like
D.
What the weather like
【简答题】It was very cold last Sunday. Paul and his friends Allen, Bill and Betty went to the lake after breakfast. They began to skate on the ice. Paul skated better than his three friends. He skated fast and...
【简答题】测得工作在放大电路中某个晶体三极管的两个电极电流如图所示。 ( 1 )求另一个电极电流,并在图中标出实际方向。 ( 2 )判断它是 NPN 还是 PNP 型管,标出 E 、 B 、 C 极。 ( 3 )估算它的 β 。
【简答题】从方框中选择合适的选项完成短文。 Last Sunday My class went to the Central Zoo last Sunday. It was our first journey and we were all very happy. 1 Halfway to the zoo we stopped at a station because the driver of the b...
【单选题】如图所示电路中,测得工作在放大状态的某个晶体三极管两个电极电流,则第三个电极的电流大小、方向和管脚自左到右的顺序分别为( )。
A.
0.03mA,流进三极管:c、e、b
B.
0.03mA,流出三极管:c、e、b
C.
0.03mA,流进三极管:e、c、b
D.
0.03mA,流出三极管:e、c、b
【简答题】完形填空。 Dear Ann, It was my birthday last Sunday. A lot of my friends came 1 and we had a wonderful party. It is a pity that you 2 come, and you missed such a nice party. Now let me send you some photos...
【单选题】—What did you do last Sunday? —It was a hard Sunday. I ______ all day. [ ]
A.
watched TV
B.
went to the restaurant
C.
studied for my math test
D.
played computer games
相关题目：