A:原子结构模型
B:物质分类模型
C:空气组成模型
D:物质酸碱度模型
——How old is your daughter?—— ______ . We had a special party for her _____ birthday last week.
读图,下列说法正确的是( )
两极点既无角速度,又无线速度。
—Do you have Mary's address?
—Sorry, I don't have it ______ me at present.
黄土高原地区最突出的优势资源是( )