用科学记数法表示：-0.00002009=（ ）．
Miss White _____ 50000 yuan building the Hope School after visiting that village. [ ]
A. took
B. paid
C. spent
下列简称为无压给煤圆筒形重介质旋流器（）
A、DSM
B、DWP
C、DBZ
D、SWIL
