1. to put down2. to put in3. to put off4. to put out5. to put on6. to put up

А в чем суть во собственно говоря?

I’ll never forget …having sailed (sail) down the Volga on that lovely summer day.

I am so sorry; I forgot …letting (let) you know.

Don’t forget …to remind (remind) them about the party.  

I remember …having seen (see) you somewhere.  

Did you remember …to water.. (water) the plants today?  

I’m sorry …………to…interruping……….. (interrupt), but can I ask you something?

Bob was sorry for …………has……shout…….. (shout) at his little sister.

He stopped ……………to smoke……….. (smoke) when he realised how dangerous it was.

Amanda stopped ………………his …….. (have) a quick snack and then continued translating the article.

\

You should try ……………exercising……….. (exercise), you may feel better.

Объяснение:

2) Len is playing tennis. He's not very good and he doesn't know the rules.
You ask: Have you played tennis before?
He says: No, this is the first time I`ve played tennis.
3) Sue is riding a horse. She doesn't look very confident or comfortable.
You ask: Have you ridden a horse before?
She says: No, this is the first time I`ve ridden a horse.
4) Maria is in London. She has just arrived and it's very new for her.
You ask: Have you been in London before?
She says: No, this is the first time I`ve come (arrived) to London.