Choose the sentence that uses a semicolon correctly. 1.A political map shows established boundaries between territories; countries; states; and cities. 2.Because maps have existed for centuries; they are a great way to study how the world has changed.
3.A physical map is a common map; however, students can best use this type of map to study the land features of individual countries. 4.Because the New World had not yet been discovered by Europeans, some early maps show only these continents; Asia, Africa, and Europe.

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.

stating you point whats is aking you to write about?