1.a little now and a little then 2.little now and little then 3.never now and 4.then now and then上面的四种表达都是正确的吗?有什么区别?

1.a little now and a little then 2.little now and little then 3.never now and 4.then now and then上面的四种表达都是正确的吗?有什么区别?
1.a little now and a little then 2.little now and little then 3.never now and 4.then now and then
上面的四种表达都是正确的吗?有什么区别?

1.a little now and a little then 2.little now and little then 3.never now and 4.then now and then上面的四种表达都是正确的吗?有什么区别?
a little now and a little then
时断时续 ,间断地,断断续续地
其他三种错误