王老师在上《绿色蝈蝈》一课前，考虑到很多学生没有见过蝈蝈这种昆虫，于是为学生准备了真实的“绿色蝈蝈”，让学生观察它的样子。这体现的教学原则是（ ）。

(单选题)A vowel is different from a consonant in English because of (单选题)______ is a language phenomenon in which words sound like wh (单选题)The Emancipation Proclamation to end the slavery plantation (单选题)A: I think English is a very useful language.B: ______. (单选题)______try using this sentence pattern now that you have lear (单选题)We don’t need air conditioning, ______. (单选题)We hadn’t met for 20 years, but I recognized her ______ I sa (单选题)It’s essential that these application forms ______ back as e (单选题)The time is not far away ______ modern communications will b (单选题)Use ______ your college has to offer, such as its library.