In the lab, don’t _________ anything without your teacher’s permission(允许)．

1. A.
   feel
2. B.
   touch
3. C.
   to touch
4. D.
   feel like

In the lab, the chemistry teacher told us what to do and ________ not to do.

1. A.
   which
2. B.
   how
3. C.
   why
4. D.
   what

In the lab the teacher showed us ________ the mixture .

1. A.
   to make
2. B.
   making
3. C.
   how to make
4. D.
   how to making

In the lab you must follow your teacher’s i ________ before doing your experiment.

In the lab, the chemistry teacher told us what to do and ________ not to do.

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