The headmaster told the boy________the a

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问题选择题

The headmaster told the boy________the angry teacher，but he refused to.[ ]

A．to apologize

B．apologize to

C．to apologize for

D．to apologize to

答案

答案：D

单项选择题 A3/A4型题

患者，男性，14岁，因外伤致左上颌中切牙缺失2个月，右上颌中切牙牙折至冠中1／3，且有轻度唇向错位，无明显松动。X线片显示，右上颌中切牙根尖部有阴影，探诊和叩诊阴性。邻牙无异常体征。

右上颌中切牙目前的处理方法是（）

A.拔除

B.观察

C.根管治疗

D.盖髓治疗

E.干尸治疗

单项选择题

In the following statements about graph operations，which one is NOT correct

A．Finding critical path is an operation on directed graph

B．Finding critical path is an operation on undirected graph

C．Spanning tree of a graph may not be unique

D．Minimum spanning tree of a graph may not be unique