he said he was at work错没错?

三句都没错.
start可做及物动词.
vt.
1.使开始,开始[O][O4][+to-v][+v-ing]
When did you start to learn English?
你何时开始学英语的?
2.引起;发起;创办
He is thinking of starting a newspaper.
他打算创办一份报纸.
3.使开始运转,启动
Do you know how to start the motor?
你会启动马达吗?
4.使流出,倒出
5.使惊跳,惊起
He started a bird as he walked in the wood.
他在林子里走时,惊动了一只鸟.
6.使松动,使脱开
7.使参赛,使出场
8.开始雇用
The bank started her as a teller.
银行起用她当出纳员.

都没错

2句话语法都没错
1.但是第二句不是过去完成时，而是现在完成时，过去完成时是had done
2.start 及物 不及物都可 表示“启动，使开始”时都是及物
比如：
It was not a propitious time to start a new business.这个时候开张不吉利。
When you start the engine, be su...

都没错

第一句没错
第二句也没错 start的宾语是a new hobby.
都可以的~~start也可以做及物动词啊~

He said he was at work没错？
I have started a new hobby 也没错？
start是可以接宾语
have started 是代表”已经“ 开始的意思

是对的！！！！！！！！！！