The changes in our chemistry lab will cost quite a lot they will save us money in the lo

问题补充：

The changes in our chemistry lab will cost quite a lot, they will save us money in the long run.

A. or

B. since

C. for

D. but

答案：

A. or

B. since

C. for

D. but

解析：根据题意,两个分句间为转折关系。in the long run意为“最终地”。