A ‣ Time in relation to now 
Now means at this moment. Then means at another moment (usually in the past).
I was born in Edinburgh. Then we moved to London. Now I live in Cambridge.
It is 10 o’clock now.
I got up four hours ago, at 6 o’clock.
An hour ago it was 9 o’clock.
two years 2014–2016
for two years from 2014 to 2016
2014 ---------> 2016
last year / last week / last Saturday next year / next week / next summer
It is July
now.
Last month it was June.
Next month it will be August.
When we talk about time in general, we talk about the past, the present and the future.
In the past people didn’t have television. People may travel to Mars in the future.
B ‣ Frequency adverbs

It always snows in Russia in winter.
It often rains in the UK.
The Ancient Romans never went to America or Australia.
C ‣ Expressions 
Notice the use of a in these expressions of frequency.
once [one time] a week: I go swimming once a week, every Saturday.
twice [two times] a day: I clean my teeth twice a day.
three times a year: I see my uncle three times a year.
four times a month: I play football four or five times a month.
I’ll be with you in a moment [a very short time].
Nora’s in Paris at the moment [now].
See you soon [in a short time]!
We met recently [not long ago].