对“下”的词性的分析，正确的一组是[ ]

老虎正要下山，老猎人躲在石岩下，抡起虎叉，突然给了老虎一下。

A． ①动词 ②方位词 ③量词

B． ①介词 ②方位词 ③量词

C． ①动词 ②助词 ③量词

D． ①介词 ②助词 ③量词

---We’ve seen many more days of blue skies recently.

　 ---True. But back in 1998, ________ Beijing started its “Defending the Blue Sky”　　　　　program, the city only ________ about 100 days a year.　　

A．which, sees

B．that, saw

C．when, saw

D．and, seeing