Mr. chan is angry so he chop his hand 5 times using the kitchen knife. when the students are naughty, he cut his 25 fingers using the cutter machine. why do mr. chan do that?

he has anger isues and should go to a anger mangement class

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.

the answer is b. the tomb is underground and dark, and its opening is covered by a heavy grate.