1 to attack

2 to accuse

3 to study

1 to besiege (a town)

1 to attack

2 to accuse

3 to charge

4 an attack (terrorist or military)

1 strategy

2 directions

3 guide

4 how-to

1 to attack

2 to assault

3 to go on the offensive

4 attack

5 assault

6 offense (sports)

1 lit. the other mountain's stone can polish jade (idiom); to improve oneself by accepting criticism from outside

2 to borrow talent from abroad to develop the nation effectively

1 lit. use sb's spear to attack his shield (idiom, derived from Han Feizi 韓非子|韩非子); turning a weapon against its owner

2 fig. to attack an opponent using his own devices

3 hoist with his own petard

1 to guard against the unexpected (idiom); just in case

2 prepared for any eventualities

1 frugality in order to prevent destitution (idiom)

1 to catch an enemy off guard with a surprise attack (idiom, from Sunzi's "The Art of War" 孫子兵法|孙子兵法[Sūn zǐ Bīng fǎ])