β受体阻断剂
A．能降低正常人血压B．对高血压病人有降压作用C．能升高正常人血压D．加快心率E．增强心肌收缩力
参考答案：B
He _________ long curly hair but my hair ______ very straight and short.
A．used to be, used to have
B．used to have , used to be
C．used to be, used to be
D．used to have , used to have
如果在删除文件或文件夹时，不希望将它们放到“回收站”中，可在选择“删除”命令或拖曳到“回收站”的同时______。
A．按住“Shift”键
B．按住“Alt”键
C．按住“Ctrl+Shift”键
D．按住“Ctrl”键
