PREP sc2 109 begin to do 与begin doing

109.
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Unlike psychiatrists, who are trained as medical doctors, psychologists have historically been forbidden from prescribing their patients drugs, but in 2002 New Mexico began to grant the privilege of prescribing to licensed, doctoral level psychologists who complete an additional training and certification program.

(A) psychologists have historically been forbidden from prescribing their patients drugs, but in 2002 New Mexico began to grant the privilege of prescribing

(B) psychologists have historically been forbidden to prescribe drugs for their patients, but in 2002 New Mexico began granting prescribing privileges

(C) psychologists have historically been forbidden to prescribe their patients drugs, but in 2002 in New Mexico, the privilege to prescribe began to be granted

(D) historically psychologists have been forbidden from prescribing their patients drugs, but in 2002 New Mexico began to grant the privilege of prescribing 答案：B

(E) historically psychologists have been forbidden from prescribing drugs for their patients, but in 2002 in New Mexico, they began granting prescribing privileges

对于B项还有不懂的就是begin to do 与begin doing。begin to do不是指一件事以前没做过现在开始做，而begin doing不是指一件事以前做了一段又停下了，现在又开始接着做吗？这里New Mexico 显然是第一次做，应当用begin to do啊。如果不是这样，请讲解一下这两者的区别。