18. I am not sure whether I can gain any profit from the investment, so I can’t make a(n) ____ promise to help you.
A. exact B. defined C. definite D. sure
investment 投資
investigate 調查
irrigate 灌溉
irritable 激怒的
navigate 航行
castigate 懲罰
mitigate 緩和，調解，減輕
sure 確信
insure 保險
ensure 確保
define 限定，下定義
final 結束的
refine 提純
finance 財政，資金
