影响土壤热量的因素（）
A.纬度和海拔高度
B.地形和地表特征
C.地面覆盖
D.其它
参考答案：A, B, C
—Mom, _____is my friend, Li Lei.
—Li Lei, _____ is my mother. [ ]
A. this; this
B. that; this
C. that; that
D. that; her
选择正确性、适当的称呼，要注意哪些原则？
