下列图形中:①平行四边形;②有一个角是30°的直角三角形;③长方形;④等腰三角形。其中是轴对称图形有几个 [ ]
A.1个
B.2个
C.3个
D.4个
答案:B
采用高压喷射注浆法加固地基时,下述()说法是正确的。
A.产生冒浆是不正常的,应减小注浆压力直至不冒浆为止
B.产生冒浆是正常的,但应控制冒浆量
C.产生冒浆是正常的,为确保注浆质量,冒浆量越大越好
D.偶尔产生冒浆是正常的,但不应持久
VRML is a (71) for 3D multimedia and shared virtual worlds on the WWW. In comparison to HTML, VRML adds the next level of interaction, structured graphics, and extra (72) (z and time) to the presentation of documents. The applications of VRML are (73) , ranging from simple business graphics to entertaining WWW page graphics, manufacturing, scientific, entertainment, and educational applications, and 3D shared virtual worlds and communities. X3D is the name under which the development of VRML is continued. X3D is based on XML and is backwards (74) with VRML. Furthermore, it is componentized, profiled, and extensible, which makes it possible to use X3D in very different (75) , from high-end visualizations to lightweight applications.
A.inconsistent
B.independent
C.applicable
D.compatible