It is vital that we _____ act out at once to protect the environment.
---Could I borrow your motor bike? ----Yes, of course, you____.
----Why is the boy crying there? ----Because____ his father.
----How is your grandmother? ----She____ for many years.
---What about____ passage? ----It’s too difficult____ passage for me.
---How do you like your Chinese teacher? ---_____.