Which type of sentence has at least one independent and one dependent clause? a. compound b. simple c. complex d. structured

The correct answer is C.

Complex sentences are formed from one independent clause and at least one dependent ( subordinate ) clause.

An independent clause can stand alone as a sentence and it makes a complete thought.

A dependent clause can not stand alone, even thought it has a subject and a verb.

The two clauses in a complex sentence are not structurally equal. Both clauses express related thoughts but only one acts as the foundation of the sentence.

An example : My sister smiled when I entered the room.

My sister smiled is an independent clause

When I  entered the room is a dependent clause

when is the subordinating conjunction

the present continuous is a verb tense which is mainly used to indicates that an action is in progress at the moment of speaking.  

it is formed using: person + verb to be (am/is/are) +verb + - ing form  

example: i am studying at this moment .

in addition, the present continuous is also used in order to express things that will or will not happen in the near future.

example: i am having dinner with some friends tonight.

the speaker sometimes   uses it   to express that an action is repeated and it causes irritation on the part of the speaker

example: my sister is constantly complaining about everything.