【推荐1】Online Free Courses

English Grammar and Style

We'll present materials that cover grammatical principles, word usage, writing style, sentence and paragraph structure and punctuation（标点符号）. Well challenge you with quizzes and writing activities that will give you strategies to enhance the quality of your writing, and invite you to participate in discussions and assess the work of your peers（同龄人）.

Length：8 weeks

Instructor: Roslyn Petelin from the University of Queensland

Academic Writing Made Easy

From structuring and organizing an academic text to avoiding common mistakes that can negatively affect your credibility this course offers a guide for those who want to improve their writing. Each week consists of video lessons, followed by exercises and tasks of assessing your peers’ work.

The course requires upper-intermediate（中高级）to advanced English.

Length: 6 weeks

Instructor: Heidi Minning from the Technical University of Munich

Preparing to Network in English

Networking in the business world is key to career success. But what is networking? And how do you do it in English? This course helps you understand the basics of networking and why it’s important. You’ll identify the key qualities you should focus on developing. Most importantly you'll grow and expand your business network and professional connections.

Length: 6 weeks

Instructor Joel Ozretich from the Univeraity of Washington

Using Emails for Networking in English

In this course, you’ll learn important strategies for writing effective emails. You’ll learn how to write messages for different audiences and understand when to be formal or direct. You'll also learn how your choice of words can change the way people view your message.

Length ：4 weeks

Instructor: Daphne Mackey from the University of Washington

【推荐2】A build-it-yourself solar still (蒸馏器) is one of the best ways to obtain drinking water in areas where the liquid is not readily available. Developed by two doctors in the U.S. Department of Agriculture, it’s an excellent water collector. Unfortunately, you must carry the necessary equipment with you, since it’s all but impossible to find natural substitutes. The only components required, though, are a 5＇ ×5＇ sheet of clear or slightly milky plastic, six feet of plastic tube, and a container — perhaps just a drinking cup — to catch the water. These pieces can be folded into a neat little pack and fastened on your belt.

To construct a working still, use a sharp stick or rock to dig a hole four feet across and three feet deep. Try to make the hole in a damp area to increase the water catcher’s productivity. Place your cup in the deepest part of the hole. Then lay the tube in place so that one end rests all the way in the cup and the rest of the line runs up — and out — the side of the hole.

Next, cover the hole with the plastic sheet, securing the edges of the plastic with dirt and weighting the sheet’s center down with a rock. The plastic should now form a cone (圆锥体) with 45-degree-angled sides. The low point of the sheet must be centered directly over, and no more than three inches above, the cup.

The solar still works by creating a greenhouse under the plastic. Ground water evaporates (蒸发) and collects on the sheet until small drops of water form, run down the material, and fall off into the cup. When the container is full, you can suck the refreshment out through the tube, and won’t have to break down the still every time you need a drink.

What is the last step of constructing a working solar still?