The phrase "a range of tough" is not correct and lacks clarity in written English.
It may be intended to describe a variety of difficult or challenging items or situations, but it needs additional context to be meaningful.
Example: "The competition presented a range of tough challenges that tested our skills."
Alternatives: "a variety of difficult" or "a selection of challenging".
Using experimental fracture data obtained from a range of tough polymers, and a computer model in which toughness, stiffness and other material parameters can be independently varied, relationships have been identified between limiting crack velocity and toughness properties of polymers.
On 14 February, Zuma announced a range of "tough" measures to deal with citizens protesting against poor services.
The APEC leaders endorsed a range of tough counter-terrorist measures that the Americans have been pushing.
But instead of dealing with those basic services, the Howard government's intervention punished the victims with a range of tough discriminatory laws.
He announced a range of tough measures to fight extremism, including examining the funding of organisations suspected of promoting radicalism, closing about 80 mosques outside government control and declaring certain mountainous zones military areas.
Even as stark differences remained between the countries on a range of tough issues, including Pakistan, trade policy, climate change and, to some degree, Iran, Mr. Obama spoke of India as an "indispensable" partner for the coming century.
The youth affairs minister, Jenny Mikakos, condemned Saturday's behaviour and said the government was developing a range of tougher measures to put a stop to it.
Perhaps intending to soften the blow, Mr. Cameron also promised a range of get-tough measures against future riots: putting more cops on the street, turning water cannons on unruly mobs, spraying rioters with dye to make them identifiable later, temporarily shut down social-networking programs and calling out the military if the police are overwhelmed.
A large range of tough matrix materials is also available.
'The lesson I have planned will help the children to use a wide range of Tough's language functions.
'The two activities have been chosen to assure that a wide range of Tough's language functions are used by the children.
