Mary, the girl, is from England.
A:eight-year-old
B:eight years old
C:eight year old
D:eight-years-old
读板块构造图,回答下列问题。
340×5=____ 375+245=____ 270÷3=____
897-389=____ 38+58= ____100-60÷5=____
长江和黄河共同流经的地形区是( )
下列不属于化学研究范畴的是( )