What happened __________ you, Mary ? You looked so sad.—I couldn’t find my MP3. It’s a present from my mother.[ ]

He seems to be a good teacher . – _____ . He has been a teacher for

I have lived in Shanghai ______.[ ]

Lily and Amy often leave _____ school_____half past seven.[ ]

The reason ______ the delay is ______ we have had difficulty in obtaining materials.