Tens of thousands of American soldiers, who don't know what is ________ them, are being sent to the Middle East.

1. A.
   happening to
2. B.
   taking place to
3. C.
   to become
4. D.
   to become of

Tens of thousands of American soldiers, who don’t know what is________ them, are being sent to the Middle East.

A. happening to     B. taking place to    C. to become 　　　　　　  D. to become of

A. happening to     B. taking place to    C. to become 　　　　　　  D. to become of

Tens of thousands of American soldiers, who don't know what is ________ them, are being sent to the Middle East.

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