27题选什么,为什么,

The news item is mainly about______.

A．east Africa"s biggest economy

B．the openness of the mining industry in Kenya

C．discoveries of rare minerals in the Mrima Hills

D．new discoveries of mineral wealth in Kenya

请帮忙给出正确答案和分析，谢谢！

According to the passage, what must the listeners do on their own？

A．Move into their dormitories.

B．Find their classrooms.

C．Memorize campus landmarks.

D．Complete their registration materials.

请帮忙给出正确答案和分析，谢谢！

可激活补体的是

A.KIR2DL

B.NKp46

C.TCR

D.MBL

E.CEA

请帮忙给出正确答案和分析，谢谢！

可传递抑制信号的是

A.KIR2DL

B.NKp46

C.TCR

D.MBL

E.CEA

请帮忙给出正确答案和分析，谢谢！

气孔是由从外面进入金属液的气体产生的。

此题为判断题(对，错)。请帮忙给出正确答案和分析，谢谢！