🧩 词语组成解析
upon
[ə'pɑn]
prep. 在…上面;当…时候;
a. 人们的；自己的
guard
[ɡɑrd]
n. 警卫;狱吏，看守;护卫队;防护装置;
vt. 保卫，守护;看守;加防护装置;谨慎使用;
vi. 警惕;警卫;
🗣️ 情景例句
What, Harry?
什么 ，Harry？
Don't keep all your eggs in one basketball.
勿孤注一掷。
and by measuring the time interval between the taps and the receipt of the echoes, the depth of the sea at that point can be calculated.
测出回声间隔的时间，便可算出该处海洋的深度。