医生过去常开巴比妥酸盐来帮助病人入睡，但现在它们很少使用了。

Doctors used to prescribe ___barbiturates to help patients sleep, but they are rarely used now.

医生警告他不要滥用巴比妥类药物来助眠。

The doctor warned him against abusing ___barbiturates to help with sleep.