A:who were take
B:that took
C:which I was take
D:that were take
“万事开头难”,但是“好的开始是成功的一半”。这句话给我们的启示是( )
设x1,x2是方程x2+4x+3=0的两根,则x1+x2=____
下列发展方向符合海南岛实际,利于可持续发展的是( )