我刚刚安装了 ubunutu 18.04 并成功安装了 R 版本 3.5.1。我在安装 R 包（例如 plotly）时遇到问题。似乎包 curl 和 httr 不可用。完整的错误信息：
> install.packages("plotly")
Installing package into ‘/home/lualeperez/R/x86_64-pc-linux-gnu-library/3.5’
(as ‘lib’ is unspecified)
also installing the dependencies ‘curl’, ‘openssl’, ‘httr’
trying URL 'https://cloud.r-project.org/src/contrib/curl_3.2.tar.gz'
Content type 'application/x-gzip' length 367047 bytes (358 KB)
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downloaded 358 KB
trying URL 'https://cloud.r-project.org/src/contrib/openssl_1.0.2.tar.gz'
Content type 'application/x-gzip' length 1194883 bytes (1.1 MB)
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downloaded 1.1 MB
trying URL 'https://cloud.r-project.org/src/contrib/httr_1.3.1.tar.gz'
Content type 'application/x-gzip' length 147593 bytes (144 KB)
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downloaded 144 KB
trying URL 'https://cloud.r-project.org/src/contrib/plotly_4.8.0.tar.gz'
Content …