Prepositions - before / after / during / while

Question 1

• during, while and for
  → We use during + NOUN (during the film).
  → We use while + VERB (while I’m reading)
• Use FOR (NOT during) + A PERIOD OF TIME (three days / two hours / a year etc.)

Answer 1

…We didn’t speak during the meal.
# but
…We didn’t speak while we were eating. (NOT during we were eating)

…We played tennis for two hours. (NOT during two hours)
…I lived in London for a year. (NOT during a year)

Question 2

• You can use before/after + -ING (before going / after eating etc.)
• We say before going (not before to go), after doing (not after to do) etc.

→ WHEN A PREPOSITION IS IMMEDIATELY FOLLOWED BY A VERB, THE VERB MUST BE IN THE GERUND FORM.
→ There are NO EXCEPTIONS to this rule.
→ A gerund is a verbal that ends in -ing and acts like a noun.

Incorrect: The company is interested in advertise on the radio.
Correct: The company is interested IN advertisING on the radio.

Answer 2

…I always have breakfast before going to work. (= before I go to work)
…After doing the shopping, they went home. (= after they did)

…Before eating the apple, I washed it carefully. (NOT before to eat)
…I started work after reading the newspaper. (NOT after to read)