以下属于选题的现实客观条件的有（）。
A.科研人员的知识结构
B.资料
C.经费
D.协作条件
参考答案：B, C, D
A few days before its anniversary, the school decided to have the buildings _____ clean as well as elegant.
A．look
B．to look
C．looked
D．being looked
某胎儿超声声像图如下，最可能的诊断为（）
A.脐带绕颈1周
B.脐带绕颈2周
C.脑积水
D.正常声像图
E.脐带绕颈3周
