铁索体是固溶体,有固溶强化现象,所以性能为硬而脆。( )
参考答案:错
若n(n≠0)是关于x方程x2+mx+2n=0的根,则n+m+4的值为( )
A.1
B.2
C.-1
D.-2
Your plan is far from satisfaction , so you must ______ more time and energy to it.
A.earn
B.spend
C.devote
D.waste