Be doubtful of investment

• 对广告有疑虑

Be doubtful of investment的用法和样例：

例句

1. Many US companies are suspicious of discounting.
   许多美国企业对收费折扣抱有疑虑。
2. The doubt was still there, in the deep recesses of her mind.
   在她的内心深处依然存有疑虑。