下列关于氧气的叙述正确的是（　　）

A．氧气可以用作燃料

B．氧气可以使带火星的木条复燃

C．红磷可以在氧气中自燃

D．氧气能溶于水

Rapid application development (RAD) systems purport to lighten the developer’s (46) by making it easy to program an application with simple intuitive steps.
RAD tools (47) the developer everything needed to construct a fully functional application quickly and easily. They make short work of modifying the developed product to (48) changes after the program is finished. Applications developed with RAD tools are constructed as they are envisioned. As an application’s real usefulness (49) , the developer armed with RAD tools should be able to (50) on new features with little fuss.

A. offer B. order C. refer D. release