抹面砂浆一般分底层、中层和面层三层进行施工，其中底层起着（）的作用，中层起着（）的作用，面层起着（）的作用。
参考答案：粘结；找平；平整装饰
用所给动词的适当形式填空。
1. Tony often ______ (go) online at weekends.
2. ______ his brother often ______ (play) computer games?
3. Mary and her sister ______ (send) emails on the computer but they ______ ______ ( not play )
games on it.
4. First, use the mouse ______ ______ (click) "new document".
5. His father ______ ______ (not watch) TV every evening but he often ______ (write) novels on his
computer.
建设工程施工过程，可能会出现不利的地质条件(如地勘未探明的软弱层)而使施工进度延误、成本增加，这种风险属于( )。
A．经济与管理风险
B．组织风险
C．工程环境风险在
D．技术风险
