一杯酒精倒出一半,剩余酒精的质量、密度、比热容和热值的变化情况是( )
A:质量、密度、比热容和热值不变
B:质量变为原来的一半,密度、比热容和热值不变
C:质量和密度变为原来的一半,比热容和热值不变
D:质量和热值变为原来的一半,密度和比热容不变
One should take ______ of his strengths to make up for his weaknesses.
—________. Only from 9:00 a.m. to 4:00 p. m. on weekends.