Andrea Possenti was able to double his money by ( ) in the Web site design company.

a)investing b) to invest c) invested d) invest

The now presentation system () by the convention center's audio visual team.

a)had installed b)will install c) was installed d) is installing

The International Clinic in Kakarta has several job () for certified dental assistants.

a)opened b) openness c) openings d) open

죄송합니다..답이 왜그런지이해가 안가서요..부탁드려요