The deep sea zone is the zone where water pressure is so high that the marine life that live here need to be able to withstand the pressure

is that the whole question?

in other words

to put it differently

for one thing

as an illustration

in this case

for this reason

to put it another way

that is to say

with attention to

by all means

important to realize

another key point

first thing to remember

most compelling evidence

must be remembered

point often overlooked

to point out

on the positive side

on the negative side

with this in mind

notably

including

like

to be sure

namely

chiefly

truly

indeed

certainly

surely

markedly

such as

especially

explicitly

specifically

expressly

surprisingly

frequently

significantly

particularly

in fact

in general

in particular

in detail

for example

for instance

to demonstrate

to emphasize

to repeat

to clarify

to explain

to enumerate

a complex sentence consists of an independent clause and one or more dependent clauses.  

to write complex sentences, we must use subordinating conjunctions.  

all the complex sentences begin with a subordinating conjunction and when it occurs, a comma must be place at the end of the dependent clause. on the contrary, if the sentence begins with an independent clause, then no comma is used.

after  

although  

as  

because  

before  

if  

since  

when  

for example,  

after she won the competition, she became very popular.  

although my father was hurt, he continued fighting for his rights.  

as all of you got a ten, you will be able to leave early today.  

before he went to the war, he asked his parents to bless him.  

if it is cold, i won’t go out.  

since you didn’t bring the homework, you will get low grades.  

when it is hot in the town, everyone goes to the beach.