Sure! Here are the intrusive sounds marked in the questions:

a. How often do you check your email inbox?
Do you think this is too **o**ften?

b. Are there any minority languages in your country?
Are they in **d**anger of extinction?

c. How effective are your oral communication skills? What can you do to improve them?
(No intrusive sound identified)

d. Does mobile technology make it easier or more difficult to switch off from study or work?
(No intrusive sound identified)

e. Is your own language difficult for other language speakers to learn?
(No intrusive sound identified)

f. How are languages best learned? Are they easier to learn when you are young?
(No intrusive sound identified)

The intrusive sounds can typically be found at the junction of words that create a smoother transition. For sounds like /j/ or /w/, they often occur between vowel sounds.