1. It isn’t necessary to do this at all. You ____ switch off your mobile phone on the train., must, don’t have to, 2. It’s OK to do this, but it’s not really necessary. You ____ shut down your laptop at night., must, don’t need to, 3. Doing this is not allowed. You ____ read text messages while driving a car., mustn’t, have to, It wasn’t necessary to do this. In the past, people ____ wear protective clothing at work, mustn’t, didn’t have to, It’s absolutely necessary to do this. In the workplace, accidents ____ be recorded and investigated., don’t need to, must.

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