While, As, As/So Long As: Describing Action

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"While" and "as" are used to describe actions that occur at the same moment that something is in progress. "While" and "as" are sometimes confused with the preposition "during." Both express the same idea, but the structures are different. "While" and "as" are time expressions and take a subject and verb. "During" is a preposition and is used with a noun or noun phrase. Take a look at the following examples to note the difference. Notice how the meaning remains the same in both structures:

During

We discussed the situation during lunch. (noun)

They are going to visit the Empire State Building during their visit to New York (noun phrase).

When / As

We discussed the situation while we were eating lunch. (full adverb time clause with subject and verb)

They are going to visit the Empire State Building as they visit New York. (full adverb time clause with subject and verb)

Future: Use "while" or "as" to state something that occurs at the same moment that something else — the main focus of the sentence — important will occur.

Time clause: present simple

Main clause: future form

Examples:

We're going to speak about the modifications as you eat lunch.
She'll work out the order details while we discuss what to do next.

Present: Use "while" or "as" to express what always happens when something else important takes place. This use of "while" and "as" is not as common as the time expression "when." Notice that the preposition "during" is often used in place of "while" or "as" to express the same idea.

Time clause: present simple

Main clause: present simple

Examples:

He usually has lunch while he takes a walk around the campus.
Angela often takes notes as the meeting progresses.

Past: "While" and "as" are used in the past to express an action that was occurring at the moment when something important happened. "While" and "as" are also used to express two actions that were happening at the same moment in the past.

Time clause: past simple OR past continuous

Main clause: past simple OR past continuous

Examples:

Doug was drying the dishes while we were watching TV.
Peter took notes as we discussed the merger.

During an Entire Period of Time

"As long as" and "so long as" are similar in use to "while" and "as." However, "as / so long as" is used for longer period of times, while "when" and "as" are used for more specific, shorter periods of time. "As / so long as" are also used to stress that something will happen, happens or happened over the entire period of time in an emphatic manner. Although examples are provided for ​the past, present and future, "as long as" and "so long as" are generally used with future forms. Notice the use of tenses:

Future: Use "so / as long as" that something will not happen for the entire period of time expressed by the time clause with "as / so long as."

Time clause: present simple

Main clause: future form

Examples:

I will never play golf as long as I live.
She will never return so long as she breathes.

Present: Use "as / so long as" to express that something happens or doesn't happen over the entire period of time that another event occurs.

Time clause: present simple

Main clause: present simple

Examples:

As long as he plays piano, I go for a walk.
She visits with her month, so long as her husband has to take care of business in town.

Past: Use "as / so long as" to describe an action that did or didn't occur over a longer period of time in the past.

Time clause: past simple

Main clause: past simple OR past continuous

Examples:

She didn't get any exercise as long as she was working 60 hours a week.
Peter didn't enjoy his company so long as he was in the house.