混凝土配合比设计，检验混凝土强度至少应用三个不同的配合比，其中一个为（）另外两个配合比的水灰比值。
A.施工配合比
B.调整后的基准配合比
参考答案：B
A family member is caring for a client diagnosed with Alzheimer's disease. Which of the following is most likely to cause the caregiver depression and role strain ？（）
A．The caregiver had a close relationship with the client before diagnosis of the illness.
B．The caregiver has no formal support, such as a visiting nurse or day care worker.
C．The caregiver understands the full reality of the disease and its inevitable progression.
D．The caregiver feels unable to control the client and unable to cope with caregiving.
煤的种类
