The following suggestions increase ’programs’ (69) and make them easier to Maintain：
1．Use a standard indention technique，blank lines，form feeds，and spaces．
2．Insert plenty of (70) into your code．

A．java code

B．C++ code

C．assemble code

D．comments

f（x）=ax²+ax-1在R上满足f（x）＜0，则a的取值范围是______．