A conjunction is a part of speech that connects words, phrases, or sentences. The easiest conjunctions to remember are "and" and "or." But there are conjunctions that do more than just connect—they give meaning to a sentence by expressing the time that something is happening: conjunctions of time.
You can easily tell if a conjunction of time is being used in a sentence because the sentence will tell you when something happens or for how long something is occurring. If you can make a "when" or "for how long" question from the sentence, and that question can be answered by the other half of the sentence, then you know that the sentence is using a conjunction of time.
When I flew in on the float plane, they were all there on the boat.
Caption 4, Alaska Revealed: Endless WavePlay Caption
Q: When were they all there on the boat? A: When I flew in on the float plane.
Be sure to put your mask on before helping them.
Caption 18, Air New Zealand: An Unexpected BriefingPlay Caption
Q: When should I be sure to put my mask on? A: Before I help them.
They have to defend their breed from predators for up to four weeks after they're born.
Captions 49-50, Evolution: Deep OceanPlay Caption
Q: When do they have to defend their breed? A: After they are born.
We have to tread lightly while filming.
Caption 40, Nature & Wildlife: Search for the Ghost BearPlay Caption
Q: When do we have to tread lightly? A: While filming.
We paddle along and we pick up trash as we goPlay Caption
Q: When do we pick up trash? A: As we go.
By the time
By the time I got to New York, I was living like a king
Captions 10-11, David Bowie: LazarusPlay Caption
Q: When were you living like a king? A: By the time I got to New York.
Note that some conjunctions of time are also phrases, not just a single word.
The conjunctions of time "until" and "till" are interchangeable and you may use either word. Many people wrongly think that "till" is just shortened version of "until," but in fact "till" is the older word, in use since the 9th century. The variant "until" has been in use since the 12th century. These two words are unusual in that they express a length of time rather than a point in time, so we should ask the question using "for how long" instead of "when."
She sat until she broke the chair.
Caption 28, Story Hour: Goldilocks and the 3 BearsPlay Caption
Q: For how long was she sitting? A: Until she broke the chair.
So he sat on a chair, till he died of despair,
Captions 20-21, Sigrid explains: The LimerickPlay Caption
Q: For how long was he sitting? A: Till he died of despair.
Don't despair, and by all means stay healthy! Go to Yabla English and find other sentences (not questions) that contain the conjunctions of time "when," "before," "after," "while," "as," "by the time," "until" and "till." Write these sentences down and practice making questions and answers from the sentences like we did above. You can also read more about "until" and "till" on the Merriam-Webster website.