Two sentences can be joined with a preposition and which.

Study the following examples.

• We bought some mangoes. We extracted the juice.
• We bought some mangoes from which we extracted the juice.

• She lent me her pen. I wrote the letter.
• She lent me her pen with which I wrote the letter.

• He picked up a stone. He killed the spider.
• He picked up a stone with which he killed the spider.

• My mother gave me her diamond necklace. I was very grateful.
• My mother gave me her diamond necklace for which I was very grateful.

• There was a towbar on the car. We attached the trailer.
• There was a towbar on the car to which we attached the trailer.

Related posts:

1. Joining two sentences using adjectives