4.We have sold most of the goods, a small portion for old customers.A. to retain B. retainC. retaining D. retains请教是使用哪个?请帮忙解释原因!

4.We have sold most of the goods, a small portion for old customers.A. to retain B. retainC. retaining D. retains请教是使用哪个?请帮忙解释原因!
4.We have sold most of the goods, a small portion for old customers.
A. to retain B. retain
C. retaining D. retains
请教是使用哪个?请帮忙解释原因!

4.We have sold most of the goods, a small portion for old customers.A. to retain B. retainC. retaining D. retains请教是使用哪个?请帮忙解释原因!
C,解释楼上的已经说清楚了

选C
retaining a small portion for old customers(留一小部分给老顾客)，其中用现在分词retaining表示伴随的状态。