Could you help me with my CET-4 writing?

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Dear all,I am a freshman in university in China. I write this ariticle because I want to improve my English and succeed in the exam. Please help me with it. Thank you. Boys and girls, attention,please! Our school's students' union is looking for students who are willing to be volunteers in the up-coming summer voluntary program. This program is organized by school's students's union. Please allow me to introduce this program to you. The aim of this program is to make the citizens aware of the environmental issues and finally take actions to protect it. During this period, the volunteers will go around the communities to propagandize the good ways to save energy or recycle the used tins or paper. At the same time, the volunteers will be designated to different departments and will be appointed with different duties. Students who are willing to apply for the positions should be energetic and strong-willed as it is a hard job. What's more, students should lead a good example. Only the qualified students can win the chance of being an excellent volunteer. Please call 12345678 if you are interested.