约如

1

网络预约车服务已经引起了对于安全问题的关注。这些问题源于现存的约车app如滴滴打车和优步引起的一系列事故。

They 've been prompted by safety concerns which have stemmed from incidents involving existing hailing apps such as Didi and Uber .
2

在过去的15年间，美国排名前50企业的总资产占美国gdp的比例由70%上升到了约130%（如图右）。

In the past 15 years the assets of the top 50 American companies have risen from around 70 % of American GDP to around 130 % ( see right-hand chart ) .
3

经典的维数约减算法，如PCA和CMDS，实现简单，可以确保发现处于高维向量空间的线性子空间上的数据集的真实几何结构。

The classical techniques for dimensionality reduction , PCA and CMDS , are simple to implement , and guaranteed to discover the true structure of data lying on or near a linear subspace of the high-dimensional input space .