1 secret know-how

2 key (to longevity)

3 secret (of happiness)

4 recipe (for success)

1 a trick

2 an ingenious method

3 know-how

4 the knack (of doing sth)

1 lit. doesn't (even) enter a single aperture (of one's head)

2 I don't understand a word (idiom)

3 it's all Greek to me

1 the seven apertures of the human head: 2 eyes, 2 ears, 2 nostrils, 1 mouth

1 lit. spouting smoke through the seven orifices (idiom)

2 fig. to seethe with anger

1 lit. doesn't (even) enter a single aperture (of one's head)

2 I don't understand a word (idiom)

3 it's all Greek to me

1 lit. spouting smoke through the seven orifices (idiom)

2 fig. to seethe with anger

1 mad about money (idiom)