风湿热最重要的临床表现是（）。
A.心脏炎
B.关节炎
C.舞蹈症
D.环形红斑
E.皮下结节
参考答案：A
果园里有43棵桃树和25棵杏树，把这些树栽8行，平均每行栽多少棵？还剩多少棵？
Laura _____ in this school since she came to China. [ ]
A. is studying
B. was studying
C. will study
D. has studied
