Adverb clauses of contrast are used mainly to contrast two things or two ideas. | In Azerbaijan, when we meet, we usually shake hands, hug or kiss each other, whereas in New Zealand they use a much warmer greeting. |
Adverb clauses of contrast are introduced by the subordinators while
and
whereas.
While is much more common than whereas. Whereas appears in academic writing. It is rare in spoken English. |
In Azerbaijan, not many people have tattoos, while in New
Zealand most Maori people
have them.
|
Explanation | Examples |
Present Perfect Progressive is used to indicate the
duration of an activity that
began in the past and continues to the present.
When the tense has this meaning, it is used with time words, such as for, since, all morning, all day, all week. |
Scientists have been studying changes in the Arctic Sea ice
for more than 100
years.
We have been discussing the problem since morning. It has been snowing all day. |
Verbs with stative meanings are not used in the progressive. Present
Perfect, not
Present Perfect Progressive, is used with stative verbs to describe the duration of
a state that began in the past and continues to the present.
|
I have known my best friend since
my childhood.
We have been friends for a long time. |
With certain verbs (live, work, teach), there is little or no difference
in meaning
between the two tenses when since or for is used.
|
I have lived in Azerbaijan since I
was born.
I have been living in Azerbaijan since I was born. |