It's hard to know how well it works by only talking about it.
光是用說的，很難知道這究竟多有效。
It is hard to know how smoothly the car runs by only driving it around the block once.
只在附近繞一圈，很難知道這輛車跑起來有多順。
It was hard to know how much weight he had lost by only looking at him.
光是看他外表，很難看出他到底瘦了多少。
It will be hard to know how good the toothpaste is for your teeth by only using it for a week.
只用這款牙膏一個禮拜很難知道它對你的牙齒有多少好處。
★延伸應用．．．．．．．．．．．．．．．．．．．．．．．．．．
It's hard to remember how many places we've traveled to by only looking at our vacation photos.
只看我們渡假的照片，很難記得我們去了多少地方。
It's hard to know how well she will do in college by only looking at her high school grades.
只看她的高中成績，很難知道她在大學的表現會有多棒。
★你知道嗎？．．．．．．．．．．．．．．．．．．．．．．．．．
口腔衛生（oral health）很重要，如果沒有好好刷牙（brush your teeth），就會有蛀牙（cavity）、齒齦炎（gingivitis/ gum disease）、牙周病（periodontitis）等問題，如此一來看牙醫（go to see a dentist）就會成為家常便飯。另外，有些潔牙產品也可學起來，包括：toothpaste（牙膏）、toothbrush（牙刷）、dental floss（牙線）、mouth wash（漱口水）。
．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．
這句話用於關心別人怎麼不開心，是不是有什麼煩惱的事情。long face 即是指「面露傷心或失望的表情」。
What's with the long face? Are you having girl trouble?
幹嘛垂頭喪氣呢？跟女孩子有關的問題嗎？
A: Hi, Tina. What's with the long face?
嗨，蒂娜。幹嘛垂頭喪氣呢？
B: Oh, my dog is sick. I'm worried about him.
我的狗生病了。我很擔心牠。
★你還可以這麼說！．．．．．．．．．．．．．．．．．．．．．．
Why the long face?
為什麼垂頭喪氣的呢？
Why do you have that look on your face?
為什麼你臉上有那種表情？
Tell me what's bothering you.
跟我說你在煩惱什麼。
What happened? Why are you so sad?
怎麼啦？你為什麼這麼難過？
It looks as if you are down in the dumps.
你看起來非常沮喪。
What's troubling you?
有什麼事讓你心煩嗎？
★你知道嗎？．．．．．．．．．．．．．．．．．．．．．．．．．
long face 就是指面露傷心或失望的表情，與中文裡的「拉長了臉」有異曲同工之妙。
．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．
★大師開講．．．．．．．．．．．．．．．．．．．．．．．．．．
-ate 作為形容詞字尾時，表示「擁有……的」、「具有某種特質或狀態的」或「充滿……的」的意思。
★必學應用字彙．．．．．．．．．．．．．．．．．．．．．．．．
considerate adj. 考慮周到的；體貼的
Tom is considerate of my feelings, but I do not want to date him.
湯姆很體貼我的感受，但我不想跟他約會。
fortunate adj. 幸運的
We were fortunate to land before the airport closed because of bad weather.
我們很幸運在機場因為天候不佳關閉前降落。
immediate adj. 立即的；即刻的
The first film was an immediate success when it hit the screen, but the second one did poorly.
第一部電影一上映就立刻大獲好評，但續集就表現不佳。
ultimate adj.最終的；極限的
Mount Everest is the ultimate challenge for a climber.
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