What's the difference between "more quickly" and "quicker"?

[ghinescu_alina@yahoo.com]

Test No. errors/elem-12 "At the Finance Company Again", question 1

Our clients than come to the office and we design a personal investment plan for them.

(a) than
(b) to
(c) personal

Test No. errors/elem-12 "At the Finance Company Again", answer 1

Our clients then come to the office and we design a personal investment plan for them.

Correct entry: then
The error was: (a) than
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which is the correct comparative of QUICKLY: MORE QUICKLY or QUICKLIER?

[Alan]

Comparative form MORE QUICKLY.
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English as a Second Language
You can read my ESL story A Rhapsody of Words