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问题 选择题

下列分子中所有原子都满足最外层8电子结构的是

A．NH3

B．PCl5

C．COCl2

D．BF3

答案

答案：C

只要分子中元素化合价的绝对值和元素原子的最外层电子数之和满足8，该原子就能满足8电子稳定结构，据此判断选项C正确，A中的氢原子，B中的P原子和D中B原子均不能满足8电子稳定结构，所以答案选C。

单项选择题

The data station usually means a (71) unit that provides data for transmission, that accepts transmitted data, and that performs all functions necessary for communication with another functional unit. Data stations may be divided into two kinds, the primary stations and the secondary stations, (72) control functions.

In (73) data link control, the primary station is the data station that supports the primary control functions of the data link, generates commands to be transmitted, and interprets received responses. Specific responsibilities assigned to the primary station include initialization of control signal interchange, organization of data flow and actions regarding error control and error recovery functions. The secondary station executes data link control functions as (74) by the primary station, interprets received commands and (75) responses to be transmitted.

（71）处填（）。

A．performance

B．functional

C．capacity

D．quality
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单项选择题

骨感不强的长脸型可在颧骨上涂上（）来增加立体感。

A.阴影色

B.提亮色

C.强调色

D.肤色
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