Some scientists think that case studies are not useful because they provide information about only one person. what do you think? what is your opinion of case studies?

well i think you should consider your own opinion and not others but ill help you out. case studies are conducted with experiments over a period of time. its reliable in a way of time and evidence. but its also not very reliable in ways of only one subject. experiments in general consist of changing something particular, such as what you are researching. so, researching or experimenting on two or more different things, gives more accurate results. more subjects more research.

it can be many reasons such as they could want they're family to live and explore more two. might just want to be nice.

3.some say for the greater good or future.

4. they might want to have they're baby,kid,family explore more. people just sacrifice.

true fact:

someone is sacrificed everyday.

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.