单项选择题
"What has happened""The window ______ but I haven't found out who ______ it."
单项选择题 One learns a language be making mistakes and ______ them.
单项选择题 We're going to the bookstore in John's car. You can come with us ______ you can meet us there later.
单项选择题 The sign reads "In case of ______ fire, break the glass and push ______ red button."