Г

[говорить под руку]  {v. phr.}

[govo`rit' `pod ruku]

 {literally} to speak to (at) someone's hand.

To say something at the wrong time; to disturb someone when he is concentrating on sth.; to distract someone by talking.

Comp.:

[put  […]

[головная боль]  {n. phr.}

[golov`naya bol']

- sth. that needs to be done and is bothering your mind;

- the work that looks as got stuck;

- the persisting problem or issue that is not going to be resolved.

See also:

[pain in the neck]  […]

[горе луковое]  {n. phr.}  {ironical}

[`gor'e `lukovoe]

 {literally}

Onion misery (or trouble).

1. Said abt. a luckless person who involves himself or/and others into troubles (even despite good intentions).

2. Said abt. a person who is  […]

[грызть гранит науки]  {v. phr.}

[gryizt' gra`nit na`uki]

 {literally}

Crack granite of science

To work hard on science study, learn the hard way. Learn in a university. Learn hard.

* /Грызть гранит науки  […]