✅ 同义词
🗣️ 情景例句
Exploring outer space is a challenge to mankind.
探索外层空间是一项向人类发出的挑战。
This part of the country is very mountainous.
国家的这部分有很多的山。
Just now we all watched you sign to show that you had received the cheque.
刚才我们大家都观察到了你为表明已收到那张支票而签名。