*keep
*keep up with和catch up with的区别？
up with和catch up with的区别？
1、意思上的区别
keep up with：紧跟；跟上，不落人之后；齐肩并进。
catch up with：赶上；追上；和…算旧账；使…最终尝到苦果。
2、用法上的区别
keep up with ：是有关于你学业／工作的水平而言。（褒义）
catch up with：是有类似于追上的意思。（中性）（或者有自贬意思）
例句：
①、keep up with
She was skipping to keep up with him.
她连蹦带跳地走着，好跟上他的步伐。
She began to walk faster, but he lengthened his stride to keep up with her
她开始加快步子，但他加大了步幅跟着她。
②、catch up with
I couldnt catch up with him.
我撵不上他。
Theres still time to catch up with them.
还有时间追上他们。
Well do our best to catch up with the advanced world levels.
我们将努力赶上世界先进水平。
英语词组可分离不可分离，如何分辨？
简单的就分为以下这两类，
一、动副短语可以分开。动副短语由动词加副词构成，有的相当于一个及物动词，有被动语态，可以支配一个宾语，如果宾语是人称代词，代词放在动词和副词之间，如果宾语为名词或不定代词，则可以放在短语动词的后面，也可以放在中间。如：He picked the book up. He picked it up.又如：work out 制定出win over 说服wipe out 消灭turn out 赶出来，结果是turn on 打开有的相当于一个不及物动词，不能支配任何宾语，无被动语态。The plane took off despite the war broke out in 1980 and lasted eight years.又如：break down 出故障come to 苏醒drop out 退出give in 让步knock off 停工 二、动副介短语不可分开。动副介短语由动词加副词加介系词构成，支配宾语的时候宾语放在介系词后面，不可分开，如：Please keep out of her old law must be done away old should keep up with the times.又如：catch up with 赶上come down with 患date back to 追溯到get along with 与……相处go on with 继续。