A conjunction is a word which merely joins two words, clauses or sentences. Note that a conjunction does not modify or qualify the words/clauses/sentences it joins.
Incorrect: He is ill since last week.
Correct: He has been ill since last week.
Incorrect: He has been working since two hours.
Correct: He has been working for two hours.
Incorrect: I have not played cricket since a long time.
Correct: I have not played cricket for a long time.
Allowed and Aloud
Allowed is a verb. To allow is to let something happen.
They allowed me to go.
Children are not allowed to enter the bar.
Whether and weather
Whether is a conjunction used to introduce alternatives.
The articles are not used:
1. Before proper, material and abstract nouns used in a general sense:
London, France, Tom, gold, rice, honesty, virtue
The definite article the is used:
6. When we refer to the imaginary geographical lines:
The Equator, The Tropic of Cancer, The Tropic of Capricorn, The Longitude, The Latitude