Complete the following phrase: 1960s1970s: Lin continued to expand his firm's specialty in prestressed concrete to broader consulting services, with projects that included conventionally reinforced concrete, structural steel, masonry, and timber-framed structures. Lin continued to expand his firm's specialty in prestressed concrete to broader consulting services, with projects that included conventionally reinforced concrete, structural steel, masonry, and timber-framed structures. ️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️ ️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️
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