tenses

Present simple
Form: He/she/it works. I work. They work
He doesn’t work. They don’t work.
Does he work? Do they work?

Use: we use the present simple tense to:
1) give information about permanent activities
the science that studies the composition, properties, and activity of organic and inorganic substances
2) describe a state that doesn’t change:
Phase describes a physical state of matter
3) talk about routine activities, repeated actions or habits
That vapor (or gas) can condense and become a drop of water

Form: I am going. He/she/it is going. They are going.
I am not going. Am I going?

Use: We use the present continuous to:

1)describe activities in progress at the moment of speaking
(She is talking to him on the phone right now.)
2)describe temporary situations:
solid is melting to form liquid
3)refer to future arrangements:
(He is starting a new job next week.)
4)describe changing situation:
(We are preparing a new compounds.
Q1: Present Simple (do) or the Present Continuous (is doing) tense.
1. What s that noise? Somebody (play)_Playing____________the piano.
2. They (go)___go___________________on holiday every winter.
4. The days (be)_____are_______________ longer in summer.
5. She often (talk)______talks_______________ to herself.