"as Kenneth sat down on the rickety old chair, it abruptly collapsed beneath him" what kind if sentence is this

It is a complex sentence.

Explanation:

There are  four basic types of sentences: simple, compound, complex, and compound-complex.

A complex sentence has one independent clause joined to a dependent clause by a subordinating conjunction.

An independent clause has a subject and a predicate, and can stand alone as a sentence, as it makes complete sense.  A dependent clause cannot stand alone.

In this case, "Kenneth sat down on the rickety old chair" is an example of an independent clause.  "as it abruptly collapsed beneath him" is a dependent clause.

i decided to stay late in the laboratory to continue my experiment with the lightbulb. at midnight, thomas edison opened the door and walked in with his head held high.

1. he leaned on the wall and observed me carefully.

2. his harsh scrutiny made me self-conscious of my skills in the lab.

3. perhaps it was just me, but the air in the laboratory began to thicken as i found myself having difficulty to breathe.

4. i turned to look at him fully as i mentally prepared myself for what my very first words would be to thomas edison.

5. the next couple of seconds shocked me. it wasn't me who spoke, but rather him and with diction i could never think of using in a simple sentence.

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hey, sorry if this was bad, i really didn't know what to write but i wanted to you. is there anything that you had to include within the excerpt?