1question only for grammer

Using 'for...' makes a prepositional phrase (prep. phr.).

A prepositional phrase consists of a preposition and a noun/ noun phrase. 'Develop' is a verb, and it can only make a verb phrase. 'Developing' is a gerund. Gerund is a verb being used as a noun by adding suffix 'ing'. Use 'developing...' can produce a noun phrase, which is the only correct phrase to follow a prep. to form a prep. phr.

2010-12-23 15:52:59 補充：
Noun phrase 'a detail plan' has no mistake. 解作「一個關於細節的計劃」。
Noun phrase 'a detailed plan' has another meaning. 解作「一個詳細的計劃」。
The adjective 'detailed' modifying a noun is correct. The noun 'detail' can be used as an adjective to modify a noun also. The choice of words makes two different meanings.

The government announced a detailed plan for the development of the surrounding area.

the government announced a detailed plan for developing the surrounding area

develop is a verb so is wrong here

for developing the surr....... = noun phrase to answer the question of what and developing is a gerund here in this sentence too
or

for the development of the surrounding area