Common mistakes are mistakes that people make all the time. There are several common mistakes in English. The most common among them are given below.

So do I, neither did I

The structure ‘so + auxiliary + subject’ is used to add a positive remark to a positive statement.

My father likes theater. So do I. (= Both my father and me like theater.)

‘I am interested in the supernatural.’ ‘So am I.’

My sister wants to be a pilot. So do I. (= Both of us want to be pilots.)

Neither do I

The structure ‘neither + auxiliary verb + subject’ is used to add a negative remark to a negative statement.

James didn’t come. Neither did Peter.

My mother doesn’t eat meat. Neither do I.

‘I haven’t seen a good movie for a long time.’ ‘Neither have I.’

He won’t be able to attend the conference. Neither will I.

Such and so

Such is used before a noun (with or without an adjective).

She is such a beautiful girl.

So is used before an adjective.

She is so beautiful.

So…that, such…that

Such in ‘such…that’ is followed by a noun phrase or its equivalent.

It was such a cold afternoon that we didn’t go out.

So in ‘so…that’ is followed by an adjective.

It was so cold that we didn’t go out.