A. they heard B. they had hear C. did they hear D. had they heard
单项选择题Which of these trains is the one （）goes to Nanjing
A. which B. of which C. of these D. that
单项选择题This book will show you （） can be used in other contexts.
A. how you have observed B. how what you have observed C. that you have observed D. how that you have observed
