So difficult______ it to acquire a large vocabulary without the help of a teacher that he was close to giving up .

All of a sudden, the thief walking behind a young and beautiful woman ______ her handbag, ______ into the crowd.

We feel _____our duty to make our country a better place.[ ]

The tourists, had enjoyed themselves so much in the botanic garden, were worn out

It was only when I reread his poemsrecently ______ I began to appreciate their beauty.