●Prior to the UML，there was no clearleading (66) language.Users had to choose from among many similar modeling languages with minor differences in overall (67) power.Most of the modeling languages shared a set of commonly accepted concepts that are expressed slightly differently in various languages.This lack of (68) discouraged new users from entering the OO market and from doing OO modeling，without greatly expanding the power of modeling.Users longed for the industry to adopt one，or a very few，broadly supported modelinglanguages suitable for (69) usage.

Some Vendors were discouraged from entering the OO modeling area because of the need to support many similar，but slightly different，modeling languages.In particular，the supply of add-ontools has been depressed because small vendors cannot afford to support many different formatsfrom many different (70) modeling tools.It is important to the entire OOindustry to encourage broadly based tools and vendors，as well as niche products that cater to the needs of specialized groups.

(66) A．programming

B．modeling

C．formal

D．intelligent

(67) A．control

B．expressive

C．conductive

D．interactive

(68) A．agreement

B．understanding

C．characteristic

D．diversitv

(69) A．distincitive

B．special-purpose

C．separate

D．general-purpose

(70) A．internal

B．external

C．front-end

D．back-end