Hi Travis, a very good attempt! To translate what you wrote in English into natural colloquial Chinese, I would suggest: 我昨天去旅遊/旅行。我很會暈車(暈船)，所以我很高興我有吃藥。 Sorry about the traditional characters - this is what I have installed on my work computer. :)

Nice try。But not quite right. First you do not use 了 with the 是。。的 pattern. 是。。的 This pattern is used to highlight the circumstances of past events. It's for when you want to get/give the answers to things like where, when, how etc, or when you want to highlight those details.你在哪里看到她的？Where did you see her？我在商店看到她的-I saw her at the shop. 你是怎么来的？-How did you get here？是飞机来的- I came by plane Note: You can omit 是 in the affirmative, but not in the negative, hence why sometimes I left out 是) Here are some more examples for you using this pattern. 他是什么时候来的？是上个月来的。 他是不是在英国生的？不是，不过小学，中学都是在英国上的。 她是什么时候去要找你的？上星期六早晨 他是在哪儿吃的午饭？在学生食堂吃的。

As Brian pointed out, there's no need to include the 的 part the way you structured your sentence. However in order to sound a little more natural, you need to say something like this: 我太高兴昨天去旅游的时候吃了晕车药/晕船药，因为我晕车/晕船。 In this case the 是。。。的 phrase is not very suitable, as Beth said, use 了 instead. Notice we don't have this Motion sickness phrase in Chinese, you need to be more specific of what you are traveling with. Also avoid using the phrase 是吃了药的 instead you should use 吃药了吗/吃过药了。If you say somebody 是吃了药的，it sounds like he/she is mentally challenged and is on something. @Beth, the 是。。。的 phrase does not highlight the circumstances of past events, you can use it to describe current circumstances too. 这些人是有钱的，那些人是没钱的。这些人是来工作的，那些人是来玩的。 Finally, just before I shut my month, avoid using dependent clause in Chinese as you'd do in English. If you absolutely have to use one, reverse the order of them in 99% of the cases will make your sentence more natural. I ate the cake that my wife got me yesterday. In Chinese we don't say things in this order normally, instead we say: 我把昨天我老婆给我买的蛋糕吃了。one sentence and that's it. If you say: 我把蛋糕吃了，就是昨天我老婆给我买的那个，then it gives the impression that you realized right after your finished the first part (我把蛋糕吃了) of the sentence that you were not specific enough and therefore need to add the second part (就是昨天我老婆给我买的那个) after it in order to avoid people asking you "what cake?" Sorry about this long novel, hope it helps, good luck with your Chinese.

表面一致的 "是...的" 句子 骨子裡卻有不同的意思 不可將其功能與意義混為一談 漢語 "是...的"句型的意義與用法是語法書籍裡專章討論的 (以上 我也用了"是...的"句型) 請參閱 劉月華 等著之 實用現代漢語語法 第四篇第三章 http://www.books.com.tw/exep/prod/china/chinafile.php?item=CN10026796 " 這件毛衣是誰的？是我的。" 跟 “他們是男的。” 與 "中國人是用筷子吃飯的。" 在語法上 沒有一句是可以混為一談的 (我又用了"是...的"句型) 以下的教學錄影 僅僅強調 "中國人是用筷子吃飯的。" 這種用法 http://www.chinese.cn/onlinelearning/article/2011-08/02/content_288810.htm

"I went traveling yesterday. I always get motion sick. I am very glad I took medicine." 本句無需應用 "是...的" 句型 我昨天去旅行 我 (一向) 患有動暈症 幸好 我(事先) 服了 (抗暈眩) 藥 motion sickness : 醫學名稱 動暈症