Final answer:
A child is typically able to undress themselves, run, walk up steps, and use two-word sentences by the age of 2 years. By this time, they are also building motor skills and language proficiency, starting to run and navigate stairs, and using up to 50 words. However, development can vary among children.
Step-by-step explanation:
Typically, a child is able to undress themselves, run, walk up steps, and use two-word sentences around the age of 2 years. By this age, toddlers are more coordinated with their movements and have achieved significant linguistic milestones. They start to run, although they fall often, and they can navigate stairs while holding on. Toddlers at this age can build towers of blocks and are starting to be able to control a spoon to feed themselves. In terms of language development, they can use up to 50 words, and typically understand many more, following simple verbal commands and starting to assist in dressing and undressing themselves.
By age 3, children have honed their gross motor skills, climbing stairs one foot per step, and have the fine motor skills to handle small objects. In cognitive development, they are forming short sentences, asking questions, and learning new words at a rapid rate.
It's important to note that child development can vary widely, and these are general milestones. Some children may develop certain skills earlier or later than others.