#四级作文#
常用高级替换词
important → crucial / essential / significant
think → maintain / contend / argue
problem → issue / challenge / concern
more and more → increasingly
because → due to / owing to / on account of
必背话题词汇
mental health（心理健康）、cultural exchange（文化交流）、procrastination（拖延症）
social practice（社会实践）、critical thinking（批判性思维）
digital literacy（数字素养）、cybersecurity（网络安全）