沿着不同的方向探索问题答案的思维叫做( )。A．形象思维 B．抽象思维 C．辐合思

下面的说法正确的个数为（　　）

①若∠α=∠β，则∠α和∠β是一对对顶角；②若∠α与∠β互为补角，则∠α+∠β=180°；③一个角的补角比这个角的余角大90°；④同旁内角相等，两直线平行．

A．1

B．2

C．3

D．4

从高温炉中取出的灰皿，在空气中冷却时间不宜太长，一般要求不超过（）min。

A.5；

B.10；

C.15；

D.2。

OOP languages that create objects, such as (1) and (2) are beginning to take hold as viable tools for programmers. To effectively reuse objects, programmers need a place to store them such as an ODBMS or a RDBMS with object oriented extensions.
Databases that handle object data not only let user store and retrieve (3) data, but also let them store objects created by OOP languages, to facilitate rapid software development and reuse, and let them (4) new multimedia applications combining multiple data types.
RDBMS vendors have developed new extensions to existing DB technology to accommodate the most common forms of (5) data.

A．C++

B．SMALLTALK

C．PASCAL

D．C

下列对步进式电机的描述中不正确的是（）。

A.是将电脉冲信号转换成角位移或直线位移的执行电机

B.常用于开环控制系统

C.控制精度高，且误差不会积累

D.定子绕组断电无励磁时，转子不受力矩，故无保持力

基因共享