单项选择题Gas does accumulate in the mines around here.
单项选择题Nerve signals may travel through nerve or muscle fibers at speeds as high as two hundred miles per hour.
单项选择题Our plan is to allocate one member of staff to handle appointments.
单项选择题In order to improve our standard of living, we have to accelerate production.
单项选择题An important part of the national government is the Foreign Service, a branch of the Department of State.