题干
You will achieve nothing ______ you work hard in a proper way.
A：because
B：if
C：when
D：unless
答案(点此获取答案解析）
D
You will achieve nothing ______ you work hard in a proper way.
A：because
B：if
C：when
D：unless
，恒容时，温度升高，H2浓度减小。下列说法正确的是
”的否定是 （ ）