∵二次根式3-x有意义，
∴3-x≥0，
∴x≤3．
故答案为：x≤3．
Between the two generations, it is often their different views of life and value _____ cause family conflicts.
A．which
B．what
C．who
D．that
在以邻苯二甲酸氢钾（KHC8H4O4）为基准物标定NaOH溶液时，下列仪器中需用操作溶液淋洗三次的是（）。
A.滴定管
B.容量瓶
C.移液管
D.锥形瓶
