波尔多液农药不能用铁制容器盛放．在该反应中铁是（ ）
A．氧化剂
B．还原剂
C．催化剂
D．发生了还原反应
答案：B
It is in the hotel _____ he stayed last night ______ he lot his mobile phone.
A．that ; that
B．that ; where
C．that; when
D．where; that
下列程序段的执行结果为 ______。 Dim m(3，3)As Integer Dim i As Integer Dim j As Integer Dim x As Integer For i=1 To 3m(i，i)=i Next For i=0 To 3For j=0 To 3 x=x+m(i，j)Next Next Print x
A．3
B．4
C．5
D．6
