【多选题】榨油厂要利用大豆期货进行买入套期保值的情形有( )。
【简答题】Nonverbal behavio r such as smile and laugh seem to cut across cultural lines. But in reality, they are often found to be not ________________.
【简答题】How did the Welsh speakers fight hard to preserve Welsh?
【单选题】变压器原、副绕组中不能改变的物理量是( )。
【多选题】关于口罩的使用事项,以下说法正确的是? ( )