( )是指期权的买方在期权到期日前不得要求期权的卖方履行期权合约,仅能在到期日当天要求期权卖方履行期权合约。
A.卖出期权
B.欧式期权
C.买入期权
D.美式期权
参考答案:B
You will find what great benefit the computer you own can be _____ each time you use it to help you work.[ ]
A. for
B. of
C. at
D. on
简述重量法测定大气降尘的原理。